Sample records for exciting rxte science

  1. Communicating the Excitement of Science

    ScienceCinema

    Michael Turner

    2010-01-08

    In this talk (which will include some exciting science) I will discuss some lessons I have learned about communicating science to scientists (in my own field and others), students, the public, the press, and policy makers in giving 500+ colloquia and seminars, 300+ public lectures and many informal presentations (including cocktail parties).

  2. RXTE Observations of Selected Blazars

    NASA Technical Reports Server (NTRS)

    Marscher, Alan P.; Jorstad, Svetlana G.

    2002-01-01

    The work completed includes the analysis of observations obtained during Cycles 4 and 5 of the Rossi X-ray Timing Explorer (RXTE). The project is part of a longer-term, continuing program to study the X-ray emission process in blazars in collaboration with Dr. Ian McHardy (U. of Southampton, UK).

  3. There's Nothing More Exciting than Science

    ERIC Educational Resources Information Center

    Wilson, Helen; Mant, Jenny; Coates, David

    2004-01-01

    The basic contention that a more imaginative, creative, and challenging approach will result in better achievement in SATs--in other words, if the children enjoy their science they will do better--was the basis of a project at Oxford Brookes University. The project was devised to encourage and enable the participating teachers to develop a…

  4. RXTE Observations of A2256

    E-print Network

    Yoel Rephaeli; Duane Gruber

    2003-05-20

    The cluster of galaxies A2256 was observed by the PCA and HEXTE experiments aboard the RXTE satellite during the period July 2001 - January 2002, for a total of 343 ks and 88 ks, respectively. Most of the emission is thermal, but the data analysis yields evidence for two components in the spectrum. Based on statistical likelihood alone, the secondary component can be either thermal or power-law. Inclusion in the analysis of data from ASCA measurements leads to a more definite need for a second component.Joint analysis of the combined RXTE-ASCA data sets yields $kT_1 = 7.9^{+0.5}_{-0.2}$ and $kT_2 = 1.5^{+1.0}_{-0.4}$, when the second component is also thermal, and $kT = 7.7^{+0.3}_{-0.4}$ and $\\alpha = 2.2^{+0.9}_{-0.3}$, if the second component is fit by a power-law with (photon) index $\\alpha$; all errors are at 90% confidence. Given the observed extended regions of radio emission in A2256, it is reasonable to interpret the deduced power-law secondary emission as due to Compton scattering of the radio producing relativistic electrons by the cosmic microwave background radiation. If so, then the {\\it effective, mean volume-averaged} value of the magnetic field in the central 1$^{o}$ region of the cluster -- which contains both the `halo' and `relic' radio sources -- is $B \\sim 0.2^{+1.0}_{-0.1}$ $\\mu G$.

  5. Mars Express - 10 Years of Exciting New Science

    NASA Astrophysics Data System (ADS)

    Chicarro, Agustin; Witasse, Olivier

    2013-04-01

    The ESA Mars Express mission was launched in 2003 and has been orbiting the planet Mars for almost ten years. All the instruments and components of the spacecraft are still working flawlessly. This first European planetary mission has been providing exciting new scientific results on the interior structure of the red planet, its surface mineralogy and geological processes, its atmospheric dynamics and chemistry, the interaction of its upper atmosphere with the solar wind, as well as the geodesy of its satellite Phobos. Also, Mars Express is helping to pave the way of future European Mars Exploration, including the Trace Gas Orbiter in 2016, the ExoMars rover in 2018 and beyond. Among the abundant Mars Express results, the Top 10 scientific highlights of the mission will be presented, addressing all fields of Mars investigation. In addition, the INSPIRE mission concept for a Mars Network Science Mission in the early 2020's will be introduced.

  6. Computer Science Programs Available at FAU's Treasure Coast Campus Florida Atlantic University's College of Engineering and Computer Science offers exciting

    E-print Network

    Fernandez, Eduardo

    Computer Science Programs Available at FAU's Treasure Coast Campus Florida Atlantic University's College of Engineering and Computer Science offers exciting degree programs in computer science.I.E.T.) and bachelor in computer science. The innovative B.I.E.T. degree program provides more hands-on, practical

  7. Excite

    NSDL National Science Digital Library

    Hot on the heels of AltaVista's Raging Search (see the May 5, 2000 Scout Report) comes another returned and (somewhat) slimmed-down search engine that focuses on relevant results. Like Raging Search, Excite's new Precision Search uses Google-style link analysis technology ("Deep Analysis") to help identify the most useful sites. Test queries produced consistently relevant results among the top few returns, though an indication of the number of total returns would be helpful, with two banner ads and (in some but not all cases) a Quick Results box on the left that could be quite handy for consumer-related searching. For instance, a search for "Plymouth" yielded links to research and comparisons, blue book values, financing, and service and repair information in the Quick Results box. I was also pleased to see that clicking on one of the other search categories (category, news, photo, audio/video) instantly produces returns for the original query, though the photo databases available seem somewhat limited compared to, say, AltaVista. While users searching for "official" sites will still do best at Google, those who also search for additional resources such as news, photos, and audio/video content may wish to give Excite Precision a run-through.

  8. RXTE Observation of the Tycho Supernova Remnant

    NASA Technical Reports Server (NTRS)

    The, Lih-Sin

    1998-01-01

    SN1006 [4] and Cas A [1, 9] supernova remnants have been shown convincingly to have a hard X-ray power-law continuum. This continuum is thought to be the synchrotron radiation from accelerated electrons of approx. 100 TeV at the shock fronts. Our goal of AO2 RXTE observation is to detect the hard X-ray continuum and to determine the nature of the continuum from Tycho SNR. A detection of a power-law continuum from Tycho SNR can strongly argue for SNRs are the source of cosmic rays with the first order Fermi acceleration as the energizing process. We report the results of our AO2 RXTE 1 x 10(exp 5) sec observation of Tycho SNR. We detect two components of the X-ray spectrum from Tycho SNR both at better than 3 omega confidence. The best two component models are: bremsstrahlung (kT=2.67 +/- 0.13 keV) + bremsstrahlung (kT=7.07 +/- 2.21/1.72 keV) or bremsstrahlung (kT=2.36 +/- 0.21/0.57 keV) + power-law (gamma=2.58 +/- 0.12/0.09 ). This result is an improvement compaxed with the previous most sensitive X-ray measurements by Ginga which shows Tycho's observed X-ray continuum requires a two-component model to yield acceptable fits with the hard component parameters being highly uncertain. Our RXTE measurements constrain all parameter within 3o, ranges. However, we cannot yet distinguish between thermal and nonthermal models for the hard component. In the followings, we describe what we accomplished in the period covered by the grant proposal.

  9. Observations of Circinus X-1 with RXTE

    E-print Network

    Hale Bradt; Robert Shirey; Alan Levine

    1998-01-27

    Data accumulated with RXTE during the active state of Cir X-1 as well as during an unusually long transition from the active state to the quiescent state are reported. The long decline from the active state allowed the source characteristics to be studied systematically as a function of intensity. The following results are presented: (1) spectral fits during entry into a dip clearly show absorption with partial covering as previously reported (Brandt et al. 1996), and (2) correlations between position in the hardness-intensity plane and the character of the power density spectrum as the source entered the quiescent state are suggestive of Z source behavior seen in LMXB sources.

  10. RXTE timing and spectroscopy of black hole binary in outburst

    NASA Technical Reports Server (NTRS)

    Swank, Jean (Technical Monitor); Miller, Jon

    2005-01-01

    Under this program, Rossi X-ray timing explorer (RXTE) made observations of the Galactic black hole X-ray binary GX 339-4. These observations were timed to be simultaneous with Chandra observations of the same source. Supporting multi-wavelength observations were also obtained using optical and radio telescopes. The RXTE data have been partially analyzed, and will be published in a paper summarizing both the Chandra and RXTE spectral results. The RXTE spectra are instrumental in defining the continuum spectrum in the Chandra data. Moreover, the timing properties measured with RXTE are essential to diagnosing the "state" of the black hole when it was observed by the array of telescopes organized for this effort.

  11. Exciting youth about science and engineering : the Stirling Engine class

    E-print Network

    Barragán, Patrick R

    2008-01-01

    The problem of a lack of science and engineering opportunities for youth has been identified. While other programs and attempted solutions exist, a novel approach involving creating self-contained project classes, called ...

  12. X-Ray Pulsar Studies With RXTE

    NASA Technical Reports Server (NTRS)

    Rappaport, Saul

    2004-01-01

    Our activities here at MIT have largely concentrated on four different binary X-ray pulsars: LMC X-4; 4UO352+3O/XPer; 4U0115+63; and X1908+075. We have also recently initiated a search for millisecond X-ray pulsations in RXTE archival data for several bright LMXBs using a new technique. Since this study is just getting under way, we will not report any results here. Using RXTE timing observations of LMC X-4 we have definitively measured, for the first time, the orbital decay of this high-mass X-ray binary. The e-folding decay time scale is very close to lo6 years, comparable to, but somewhat longer than, the corresponding orbital decay times for SMC X-1 and Cen X-3. We find that the orbital decay in LMC X-4 is likely driven by tidal interactions, where the asynchronism between the orbital motion and the rotation of the companion star is maintained by the evolutionary expansion of the companion. Under NASA grant NAGS7479 we carried out RXTE observations of X Per/4U0352+30 in order to track the pulse phase over a one year interval. This effort was successful in tentatively identifying a N 250-day orbital period. However, due to the fact that the observing interval was only somewhat longer than the orbital period, we asked for the observations of X Per to continue as public, or non-proprietary observations. Dr. Jean Swank kindly agreed to the continuation of the observations and they were carried out on a less frequent basis over the next year and a half. After 72 separate observations of X Per, we have the orbital period and semimajor axis firmly determined. In addition, we were able to measure the orbital eccentricity-which turns out to be remarkably small (e = 0.10) for such a wide binary orbit. This has led us establish the birth of a neutron star with a very small (or zero) natal kick.

  13. RXTE Observations of Several Strong Flares from the TeV Blazar 1ES 1959+650

    NASA Technical Reports Server (NTRS)

    Krawczynski, Henric

    2004-01-01

    Responding to the RXTE Cycle 7 NASA Research Announcement, we proposed to use the RXTE X-ray telescopes to intensively observe the TeV Gamma-ray Blazars Markarian 421, Markarian 501, 1ES 1959+650 and 1ES 1426+428, when their X-ray or TeV Gamma-ray fluxes would surpass preset trigger thresholds. In May and June, 2002, the Blazar 1ES 1959+650 (z=0.048) showed a series of spectacular X-ray and gamma-ray flares. Following the detection of a strong Gamma-ray flare on May 16 and 17 with the VERITAS 10 m Cherenkov Telescope, we invoked intensive RXTE observations, as well as complementary radio, optical and GeV/TeV Gamma-ray observations. From May 18 to August 14, more than 150 ksec RXTE observations were taken, yielding a unique data set with simultaneous RXTE and GeV/TeV Gamma-ray coverage.We used the financial support from the ADP program of NASA s Office for Space Science to perform a comprehensive analysis of the RXTE data. We studied in detail the temporal and spectral characteristics of the source. We collected multiwavelength data from a large number of collaborators, and performed a detailed cross-correlation analysis. Eventually, we interpreted the results in the framework of a Synchrotron-Self Compton model. The most important discovery of our research has been the detection of an orphan gamma-ray flare , not associated with an X-ray flare. The discovery showed conclusively that most models invoked to describe the non-thermal emission from blazars are overly simplistic.

  14. RXTE Observations of M87: Investigating the Nonthermal Continuum

    NASA Technical Reports Server (NTRS)

    Reynolds, Christopher S.

    2001-01-01

    This is the final report for NASA grant, awarded for the RXTE Cycle 3 Guest Observer Program, "Investigating the nonthermal continuum".It supported analysis of RXTE observations of the nearby giant elliptical galaxy M87 with the RXTE satellite. The main aim of these observations was to search for non-thermal emission from the core of M87 and the famous jet. This grant also partially funded supporting theoretical work. The observational campaign was performed in December 1997 and January 1998. The results of our detailed analysis were submitted to the Astrophysical Journal in November 1998, and accepted for publication in March 1999. The paper was published in August 1999.

  15. Using Space Science to Excite Hispanic Students in STEM

    NASA Astrophysics Data System (ADS)

    Reiff, P. H.; Galindo, C.; Garcia, J.; Morris, P. A.; Allen, J. S.

    2013-05-01

    Over the past ten years, NASA and its cosponsors have held an annual "NASA Space Science Day" at the University of Texas at Brownsville. The event is held over two days, with the Friday evening program featuring a space scientist or astronaut, this year Joe Acaba, giving a public lecture (plus a free planetarium show). The Saturday event starts with a keynote speech from the same speaker. Then the students circulate among six or seven hands-on workshops, plus a scheduled trip to the "Demo room" where NASA missions show their materials, and a planetarium show in the Discovery Dome. The students, 4th through 8th graders, are drawn from schools all across south Texas, and have included students coming as far as Zapata, with a four-hour bus ride each way. Over the ten years of the program, more than 5000 students have been reached. Most of the hands-on activities are led by undergraduate student mentors. The university students (42 in 2013) received science and engineering content and mentor training on the activities at Johnson Space Center before the January event. In addition, an additional 40 local high school students helped with activities and with escorting each group of students from one activity station to the next. The program has been so successful that students have "graduated" from participant, to volunteer, and now to University student mentor. Most of the mentors go on to complete a degree in a STEM discipline, and many have gone on to graduate school. Thus the mentors not only help with the program, they are beneficiaries as well. The program is being expanded to reach other underserved communities around the US, with its first "expansion" event held in Utah in 2011.; Puerto Rican Astronaut Joe Acaba and the Discovery Dome were two of the highlights for the students.

  16. RXTE Observations M87: Investigating the Non-Thermal Continuum

    NASA Technical Reports Server (NTRS)

    Reynolds, Christopher S.

    2001-01-01

    This is the final report for NASA grant NAG5-7329, awarded for the RXTE Cycle 3 Guest Observer Program, "RXTE Observations of M87: Investigating the nonthermal continuum". This grant totaled $8000 and was spent over 3 years (4/1998-4/2001). It supported analysis of RXTE observations of the nearby giant elliptical galaxy M87 with the RXTE satellite. The main aim of these observations was to search for non-thermal emission from the core of M87 and the famous jet. This grant also partially funded supporting theoretical work. The observational campaign was performed in December 1997 and January 1998, and we were given the final data tape in April 1998. Sebastian Heinz (then a graduated student in our group) and I started to work on the data immediately. The results of our detailed analysis were submitted to the Astrophysical Journal in November 1998, and accepted for publication in March 1999. Tile paper was published in August, 1999. The journal reference is: A RXTE study of N187 and the core of the Virgo cluster, Reynolds C.S.,Heinx S., Fabian A.C., Begelman M.C., 1999, ApJ, 102, 1999. During this first year of the project, this grant supported Mr. Heinz's travel to the Paris Texas Symposium in December 1998, as well as providing funds for necessary maintenance of our computer system.

  17. RXTE Observations of MAXI J1836-194

    NASA Astrophysics Data System (ADS)

    Strohmayer, T. E.; Smith, E. A.

    2011-08-01

    RXTE observed the recently discovered X-ray transient MAXI J1836-194 (Atel #3611, #3613, #3614) beginning at 11:08:01 (UT) on August 31, 2011, for a total of 6 ksec of good exposure over two RXTE orbits. We detect the source at a count rate of approximately 140 cts/sec (1PCU), and variability is evident with the eye. A power spectral study shows significant flat-topped, band-limited noise breaking to a power-law below 5 Hz with evidence for a weak QPO at 0.5 Hz, above the break.

  18. Low-mass X-ray Binaries with RXTE

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Below are the publications which directly and indirectly evolved from this very successful program: 1) 'Search for millisecond periodicities in type I X-ray bursts of the Rapid Burster'; 2) 'High-Frequency QPOs in the 2000 Outburst of the Galactic Microquasar XTE J1550-564'; 3) 'Chandra and RXTE Spectroscopy of Galactic Microquasar XTE 51550-564 in Outburst'; 4) 'GX 339-4: back to life'; 5) 'Evidence for black hole spin in GX 339-4: XMM-Newton EPIC-PN and RXTE spectroscopy of the very high state'.

  19. RXTE Discovery of Pulsations from SGR 0418+5729

    NASA Astrophysics Data System (ADS)

    Gogus, Ersin; Woods, Peter; Kouveliotou, Chryssa

    2009-06-01

    Following the Fermi GBM/Konus/Swift detection of bursts from the new Soft Gamma Repeater SGR 0418+5729 (van der Horst et al. 2009, GCN #9499) we triggered our SGR ToO Program with RXTE. A 6.8 ks RXTE observation started on 2009 June 10, 03:42:56 UT. We detect strong, coherent pulsations from the new SGR in the 2-10 keV PCA data at 0.110152(2) Hz, corresponding to a spin period of 9.0783(1) sec. The pulse morphology is complex showing two asymmetric maxima per cycle.

  20. Gamma-ray Burst Positions from the ASM on RXTE

    E-print Network

    Hale V. Bradt; Donald A. Smith

    1999-05-20

    The RXTE/ASM has detected and positioned 14 confirmed GRB bursts (at this writing, Jan. 1999) including six whose positions were comunicated to the community 2 to 32 hours after the burst. Two of these latter bursts led to measurements of optical red shifts but one, despite an easily detected x-ray afterglow, produced no detectable optical or radio afterglow.

  1. RXTE Timing of New Energetic Pulsars for Glast (core Program)

    NASA Astrophysics Data System (ADS)

    GLAST is expected to detect many new gamma-ray pulsars, and hopefully solve problem of unidentified gamma-ray sources. However, detecting pulsars requires phase-coherent monitoring to provide a pulse ephemeris with which to fold the gamma-ray data. This is because of the paucity of gamma-ray photons, which demands ~year long integration times, coupled with the timing noise and glitches seen in the best GLAST targets. For radio-quiet pulsars, regular RXTE monitoring is the only practical option for coherent timing. We propose to time any radio- quiet energetic young X-ray pulsar discovered during Cycle 12 with RXTE, to provide an ephemeris for GLAST. These timing observations will be interesting for measuring braking indexes and studying glitching behavior in energetic pulsars.

  2. RXTE Timing of New Energetic Pulsars for Glast

    NASA Astrophysics Data System (ADS)

    Kaspi, Victoria

    GLAST is expected to detect many new gamma-ray pulsars, and hopefully solve problem of unidentified gamma-ray sources. However, detecting pulsars requires phase-coherent monitoring to provide a pulse ephemeris with which to fold the gamma-ray data. This is because of the paucity of gamma-ray photons, which demands ~year long integration times, coupled with the timing noise and glitches seen in the best GLAST targets. For radio-quiet pulsars, regular RXTE monitoring is the only practical option for coherent timing. We propose to time any radio- quiet energetic young X-ray pulsar discovered during Cycle 12 with RXTE, to provide an ephemeris for GLAST. These timing observations will be interesting for measuring braking indexes and studying glitching behavior in energetic pulsars.

  3. Bat Triggered Target of Opportunity Observations with RXTE

    NASA Astrophysics Data System (ADS)

    Krimm, Hans

    We propose to trigger RXTE PCA observations of new galactic sources discovered as part of the Hard X-ray Transient Monitor of the Burst Alert Telescope (BAT) on the Swift satellite. BAT can provide an early hard X-ray (15-50 keV) trigger on a moderately bright new source. We need the complementary high sensitivity timing data from RXTE to distinguish between various models for the origin of the new transient. By studying the temporal properties of the source in the early turn-on phase we can distinguish between the early accretion disk flow of a black hole candidate, and the periodic emission from a millisecond pulsar or longer period pulsar. This will allow us to rapidly identify the source class and to publish results from the turn-on phase of newly discovered galactic transients.

  4. "XMM/RXTE Observations of GX 339-4"

    NASA Technical Reports Server (NTRS)

    Nowak, M. A.; Corbel, S.; Fender, R.; Wilms, J.; Kuster, M.; Bailyn, C.; Coppi, P.

    2005-01-01

    In March 2003, we performed two simultaneous XMM/RXTE observations of the black hole candidate GX 339-4. Our goal is to compare these data to our prior simultaneous RXTE/ASCA observations (Nowak, Wilms & Dove, 2002). These observations were carried out in timing mode, as opposed to burst mode, and are more complex to analyze than we expected. Specifically, the data suffered from a number of telemetry dropouts (in fact, the standard archive processing failed on these data, and more than a year passed from the time of the observations before the data was delivered to us). Furthermore, the core of the EPIC PSF suffers slightly from pileup and gain shifts. We continue to work on this data, however, and anticipate publishing it within the next academic year. Here we highlight our ongoing work and outline our plans for publication.

  5. Bat Triggered Target of Opportunity Observations with RXTE (core Program)

    NASA Astrophysics Data System (ADS)

    We propose to trigger RXTE PCA observations of new galactic sources discovered as part of the Hard X-ray Transient Monitor of the Burst Alert Telescope (BAT) on the Swift satellite. BAT can provide an early hard X-ray (15-50 keV) trigger on a moderately bright new source. We need the complementary high sensitivity timing data from RXTE to distinguish between various models for the origin of the new transient. By studying the temporal properties of the source in the early turn-on phase we can distinguish between the early accretion disk flow of a black hole candidate, and the periodic emission from a millisecond pulsar or longer period pulsar. This will allow us to rapidly identify the source class and to publish results from the turn-on phase of newly discovered galactic transients.

  6. RXTE Observations of LMC X-1 and LMC X-3

    NASA Technical Reports Server (NTRS)

    Wilms, J.; Nowak, M. A.; Dove, J. B.; Pottschmidt, K.; Heindl, W. A.; Begelman, M. C.; Staubert, R.

    1999-01-01

    Of all known persistent stellar-mass black hole candidates, only LMC X-1 and LMC X-3 consistently show spectra that are dominated by a soft, thermal component. We present results from long (170 ksec) Rossi X-ray Timing Explorer (RXTE) observations of LMC X-1 and LMC X-3 made in 1996 December. The spectra can be described by a multicolor disk blackbody plus an additional high-energy power-law. Even though the spectra are very soft (Gamma approximately 2.5), RXTE detected a significant signal from LMC X-3 up to energies of 50 keV, the hardest energy at which the object was ever detected. Focusing on LMC X-3 , we present results from the first year of an ongoing monitoring campaign with RXTE which started in 1997 January. We show that the appearance of the object changes considerably over its approximately 200 d long cycle. This variability can either be explained by periodic changes in the mass transfer rate or by a precessing accretion disk analogous to Her X-1.

  7. RXTE Observations of LMC X-1 and LMC X-3

    NASA Technical Reports Server (NTRS)

    Wilms, J.; Nowak, M. A.; Dove, J. B.; Pottschmidt, K.; Heindl, W. A.; Begelman, M. C.; Staubert, R.

    1998-01-01

    Of all known persistent stellar-mass black hole candidates, only LMC X-1 and LMC X-3 consistently show spectra that are dominated by a soft, thermal component. We present results from long (170 ksec) Rossi X-ray Timing Explorer (RXTE) observations of LMC X-1 and LMC X-3 made in 1996 December. The spectra can be described by a multicolor disk blackbody plus an additional high-energy power-law. Even though the spectra are very soft (Gamma approximately 2.5), RXTE detected a significant signal from LMC X-3 up to energies of 50 keV, the hardest energy at which the object was ever detected. Focusing on LMC X-3, we present results from the first year of an ongoing monitoring campaign with RXTE which started in 1997 January. We show that the appearance of the object changes considerably over its approximately 200d long cycle. This variability can either be explained by periodic changes in the mass transfer rate or by a precessing accretion disk analogous to Her X-1.

  8. Getting the Public Excited about Science through News Stories about Global Sporting Events

    NASA Astrophysics Data System (ADS)

    Dufoe, A.

    2014-12-01

    News is all about opportunity, and no topic can pull an audience together across ages and countries better than international sports competitions. Sports news excites people, generating conversations at work and at home throughout the duration of the competition. The popularity of these sporting events engages the general public through print and video channels, but it also offers the opportunity for news beyond the competition results - specifically, how science and scientific principles and properties tie in to the sport. Take the Olympics and the World Cup, for example. News sites were more motivated to write and run stories about the aerodynamics of a soccer ball or science behind Olympic bobsleds because these topics are timely: timeliness is one of the most important reasons news stories get written and published. And analysis of even a small sample of news stories and the language used will show why the news organization posted the story. Since the science content is being translated for the general public, the topics can provide a more general explanation of the science behind sporting events, equipment and the act of doing the sport. But beyond international sporting events, even the opening day of baseball, first night of ice hockey, the start of football and the beginning of basketball season provide opportunities for news organizations to provide science news to the public. Scientists need to get ready to collaborate with journalists to tap into the next big sporting event - Super Bowl XLIX. Although it has not been determined which teams are playing yet, scientists can start preparing content-rich stories on the physics of a football, the climate of Phoenix, Arizona, and the green mission of the University of Phoenix Stadium (the location of Super Bowl 2015). This is an opportunity for scientists and media outlets to add science content knowledge to the hype of the event. After the Super Bowl comes the 2016 Summer Olympics in Rio, which has already been in the news with reporters covering water contamination issues and sustainable construction projects.

  9. Echo Tomography of Hercules X-1: Mapping the Accretion Disc with RXTE and HST

    NASA Technical Reports Server (NTRS)

    Vrtilek, S.

    2000-01-01

    A paper based on the RXTE results contents the following and are ready for submission to ApJ: "Possible Detection of Companion Star Reflection from Hercules X-1 with RXTE". A paper combining July 1998 and July 1999 observations (including the RXTE results for both years) is nearly ready for submission to ApJ: The July 1998 and July 1999 Multiwavelength Campaigns on Hercules X-I/HZ Herculis. The July 1999 observations took place during an anomalous X-ray low state and the RXTE and EUVE data are consistent with X_ray reflected from the surface of the companion star.

  10. Search for QPOs in Magnetar Bursts with Swift and RXTE

    NASA Astrophysics Data System (ADS)

    Ibrahim, Alaa

    We have performed a QPO search in the magnetar bursts observed by Swift and RXTE. We found a low frequency QPO candidate at 45 Hz with 11% amplitude in one burst. We present the results of our search including stringent upper limits and discuss its veracity of the candidate feature in light of aliasing effects that could produce such a feature in bursts whose duration are at a comparable time scale. (*) This contribution presents results from students projects carried out during the 8th COSPAR Capacity Building Workshop on Space Astrophysics with NASA & ESA Missions: Swift, Chandra & XMM Newton (Jan. 20-Feb. 2, 2008; Alexandria, Egypt; http://cais.cu.edu.eg/astro)

  11. The RXTE All Sky Monitor: First Year of Performance

    E-print Network

    Ronald A. Remillard; Alan M. Levine

    1997-07-30

    The RXTE All Sky Monitor provides a public database that includes more than one year of X-ray monitoring observations (2-12 keV) of X-ray binaries and a few active galactic nuclei. The instrument operates with a 40% duty cycle, and the exposures yield roughly 5 celestial scans per day. There have been 109 source detections, including 16 X-ray transients, the majority of which are recurrent cases. The two sources of relativistic radio jets have exhibited particularly complex light curves and new types of emission states. Progress has been achieved in understanding the outburst mechanism via the reported detection of an optical precursor to the April 1996 X-ray outburst in GRO J1655-40. The ASM has also detected state changes in both Cyg X-1 and Cyg X-3, leading to new constraints on the accretion disk geometry associated with the ``soft/high'' state. X-ray variations are seen in extragalactic nuclei, such as NGC4151 and Mkn501, providing new opportunities for multifrequency timing or spectral studies. The ASM archive empowers observers with the opportunity for state-dependent observing programs with RXTE and other instruments. The ASM also provides a long-term context for source behavior, and this knowledge may be crucial in shaping the interpretation of brief observations with other telescopes.

  12. XTE Observations of Intermediate Polars: RXTE TOO Observations of Supernovae

    NASA Technical Reports Server (NTRS)

    Schlegel, E.; Swank, Jean (Technical Monitor)

    2002-01-01

    Two intermediate polar cataclysmic variables, PQ Gem and AO Psc, were observed jointly with the Rossi X-ray Timing Explorer (RXTE) and ground-based photometry. The analysis of intermediate polars (IPs) is complex because these objects exhibit light curves that behave differently as a function of energy and that behave differently when phased on the orbital or on the spin periods. The presence of two periods in one system is essentially equivalent to analyzing two different X-ray sources. A preliminary analysis of the PQ Gem data was carried out and presented at the Annapolis Workshop on Magnetic Cataclysmic Variables. The final analysis of the data were held up by problems with the background estimation. The RXTE PCA team has released a new version of the background estimator. The PQ Gem must be reanalyzed using the new background. We have also installed a spectral model that calculates the expected emission from an accretion column. That model is undergoing final testing before we apply it to the data.

  13. Analysis of RXTE data on Clusters of Galaxies

    NASA Technical Reports Server (NTRS)

    Petrosian, Vahe

    2004-01-01

    This grant provided support for the reduction, analysis and interpretation of of hard X-ray (HXR, for short) observations of the cluster of galaxies RXJO658--5557 scheduled for the week of August 23, 2002 under the RXTE Cycle 7 program (PI Vahe Petrosian, Obs. ID 70165). The goal of the observation was to search for and characterize the shape of the HXR component beyond the well established thermal soft X-ray (SXR) component. Such hard components have been detected in several nearby clusters. distant cluster would provide information on the characteristics of this radiation at a different epoch in the evolution of the imiverse and shed light on its origin. We (Petrosian, 2001) have argued that thermal bremsstrahlung, as proposed earlier, cannot be the mechanism for the production of the HXRs and that the most likely mechanism is Compton upscattering of the cosmic microwave radiation by relativistic electrons which are known to be present in the clusters and be responsible for the observed radio emission. Based on this picture we estimated that this cluster, in spite of its relatively large distance, will have HXR signal comparable to the other nearby ones. The planned observation of a relatively The proposed RXTE observations were carried out and the data have been analyzed. We detect a hard X-ray tail in the spectrum of this cluster with a flux very nearly equal to our predicted value. This has strengthen the case for the Compton scattering model. We intend the data obtained via this observation to be a part of a larger data set. We have identified other clusters of galaxies (in archival RXTE and other instrument data sets) with sufficiently high quality data where we can search for and measure (or at least put meaningful limits) on the strength of the hard component. With these studies we expect to clarify the mechanism for acceleration of particles in the intercluster medium and provide guidance for future observations of this intriguing phenomenon by instrument on GLAST. The details of the nonthermal particle population has important implications for the theories of cluster formation, mergers and evolution. The results of this work were first presented at the High Energy Division meeting of the American astronomical Society at Mt. Tremblene, Canada (Petrosian et al. 2003). and in an invited review talk at the General Assembly of the International Astronomical Union at Sydney, Australia (Petrosian, 2003). A paper describe the observations, the data analysis and its implication is being prepared for publication in the Astrophysical Journal.

  14. Chandra and RXTE Observations of X-ray Novae

    E-print Network

    Jeffrey E. McClintock

    2001-09-24

    We discuss new observations of X-ray novae with Chandra which provide strong evidence that black holes have event horizons. The evidence is based on the finding that black hole X-ray novae in quiescence are approximately 100 times fainter than equivalent neutron star X-ray novae. The advection-dominated accretion flow model provides a natural explanation for this difference. RXTE observations of XTE J1550-564 in the very high state, which were obtained during the 1998-1999 outburst of the source, reveal an extraordinarily tight correlation between the central frequency of the low frequency QPO and the soft, non-power-law flux in the 2-20 keV band. We discuss the nature of this soft spectral component and suggest the importance of obtaining direct observations of it at low energies (E < 2 keV) at the first available opportunity.

  15. Coordinated Millisecond RXTE+OPTICAL Observations of Persistent LMXB

    NASA Astrophysics Data System (ADS)

    Spruit, Hendrik

    In RXTE+optical observatipons of XTE J1118+480 we found the visible light to be strongly correlated with the X-rays on time scales of 0.03 - 5s. The short time scales, and a `premonition dip' in the visible preceding the X-rays, turn out to be difficult to understand in existing models. Simultaneous fast X-ray+optical obervations thus may give new clues on the poorly understood inner regions of the accretion flow in XRB, and their relation to outflows. We propose to observe for this purpose the brightest persistent low-mass black hole accreters, and two well studied neutron star accreters. (Cyg X-1, GX 339-4, Cyg X- 2 and the neutron star jet source Cir X-1).

  16. Simultaneous Fuse/rxte Observations of Magnetic Cataclysmic Variables

    NASA Astrophysics Data System (ADS)

    Mukai, Koji

    In magnetic cataclysmic variables (mCVs), the accretion stream near the white dwarf is irradiated by the X-rays to produce strong emission lines in the far ultraviolet. These UV emission lines contain information on the kinematics, the abundances, and the physical conditions of the stream. We have therefore started a multi-year FUSE campaign to observe selected mCVs which highlight different aspects and/or show unique characterstics. In this context, we have submitted FUSE AO-2 proposals on PQ Gem and AE Aqr; to take full advantage of the FUV data, we need the knowledge about the photoionizing continuum, i.e., X-rays. We therefore propose simultaneous RXTE observations of these proposed FUSE targets.

  17. Absolute Timing of the Crab Pulsar with RXTE

    NASA Technical Reports Server (NTRS)

    Rots, Arnold H.; Jahoda, Keith; Lyne, Andrew G.

    2004-01-01

    We have monitored the phase of the main X-ray pulse of the Crab pulsar with the Rossi X-ray Timing Explorer (RXTE) for almost eight years, since the start of the mission in January 1996. The absolute time of RXTE's clock is sufficiently accurate to allow this phase to be compared directly with the radio profile. Our monitoring observations of the pulsar took place bi-weekly (during the periods when it was at least 30 degrees from the Sun) and we correlated the data with radio timing ephemerides derived from observations made at Jodrell Bank. We have determined the phase of the X-ray main pulse for each observation with a typical error in the individual data points of 50 microseconds. The total ensemble is consistent with a phase that is constant over the monitoring period, with the X-ray pulse leading the radio pulse by 0.01025 plus or minus 0.00120 period in phase, or 344 plus or minus 40 microseconds in time. The error estimate is dominated by a systematic error of 40 microseconds, most likely constant, arising from uncertainties in the instrumental calibration of the radio data. The statistical error is 0.00015 period, or 5 microseconds. The separation of the main pulse and interpulse appears to be unchanging at time scales of a year or less, with an average value of 0.4001 plus or minus 0.0002 period. There is no apparent variation in these values with energy over the 2-30 keV range. The lag between the radio and X-ray pulses ma be constant in phase (i.e., rotational in nature) or constant in time (i.e., due to a pathlength difference). We are not (yet) able to distinguish between these two interpretations.

  18. A bright thermonuclear X-ray burst simultaneously observed with Chandra and RXTE

    E-print Network

    in ’t Zand, J. J. M.

    The prototypical accretion-powered millisecond pulsar SAX J1808.4?3658 was observed simultaneously with Chandra-LETGS and RXTE-PCA near the peak of a transient outburst in November 2011. A single thermonuclear (type-I) ...

  19. Markarian 501 in X-ray bright state - RXTE observations

    E-print Network

    G. Lamer; S. J. Wagner

    1998-01-02

    Mrk 501 has been in a state of very high flux in X-rays and VHE gamma-rays during 1997. In July 1997 near its hitherto maximum X-ray brightness intense multifrequency observations of Mrk 501 have been performed at radio, near infrared, optical, X-ray, and VHE gamma-ray frequencies. Here we report on Rossi X-ray Timing Explorer (RXTE) observations carried out in 1997 between July 11 and July 16. The X-ray spectrum has been well detected up to 100 keV and is best described by a broken power law with spectral indices alpha1=0.70 and alpha2=0.94 below and above the break energy 5.8 keV. The X-ray flux from Mrk 501 declined and flared by about 30% within about 3 days each, showing an unusual anti-correlation between flux and spectral hardening of both power law components. The break energy remained constant. The observed broad band and X-ray spectra confirm recent observations, that the synchrotron component in Mrk 501 can extend up to energies of 100 keV with the maximum power being emitted at hard X-rays. On longer time-scales the cut-off frequency of the synchrotron spectrum changes by more than two orders of magnitude.

  20. ADVANCES IN THE RXTE PROPORTIONAL COUNTER ARRAY CALIBRATION: NEARING THE STATISTICAL LIMIT

    SciTech Connect

    Shaposhnikov, Nikolai [CRESST and Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Jahoda, Keith; Markwardt, Craig; Swank, Jean; Strohmayer, Tod, E-mail: nikolai.v.shaposhnikov@nasa.gov [Astrophysics Science Division, Goddard Space Flight Center, NASA, Greenbelt, MD 20771 (United States)

    2012-10-01

    During its 16 years of service, the Rossi X-Ray Timing Explorer (RXTE) mission has provided an extensive archive of data, which will serve as a primary source of high cadence observations of variable X-ray sources for fast timing studies. It is, therefore, very important to have the most reliable calibration of RXTE instruments. The Proportional Counter Array (PCA) is the primary instrument on board RXTE which provides data in 3-50 keV energy range with submillisecond time resolution in up to 256 energy channels. In 2009, the RXTE team revised the response residual minimization method used to derive the parameters of the PCA physical model. The procedure is based on the residual minimization between the model spectrum for Crab Nebula emission and a calibration data set consisting of a number of spectra from the Crab and the on-board Am{sub 241} calibration source, uniformly covering the whole RXTE mission operation period. The new method led to a much more effective model convergence and allowed for better understanding of the PCA energy-to-channel relationship. It greatly improved the response matrix performance. We describe the new version of the RXTE/PCA response generator PCARMF v11.7 (HEASOFT Release 6.7) along with the corresponding energy-to-channel conversion table (version e05v04) and their difference from the previous releases of PCA calibration. The new PCA response adequately represents the spectrum of the calibration sources and successfully predicts the energy of the narrow iron emission line in Cas-A throughout the RXTE mission.

  1. Advances in the RXTE Proportional Counter Array Calibration: Nearing the Statistical Limit

    NASA Technical Reports Server (NTRS)

    Shaposhnikov, Nikolai; Jahoda, Keith; Markwardt, Craig; Swank, Jean; Strohmayer, Tod

    2012-01-01

    During its 16 years of service Rossi X-ray Timing Explorer (RXTE) mission has provided an extensive archive of data, which will serve as a primary source of high cadence observation of variable X-ray sources for fast timing studies. It is, therefore, very important to have the most reliable calibration of RXTE instruments. The Proportional Counter Array (PCA) is the primary instrument on-board RXTE which provides data in 2-50 keY with higher than millisecond time resolution in up to 256 energy channels. In 2009 RXTE team revised the response residual minimization method used to derive the parameters of the PCA physical model. The procedure is now based on the residual minimization between the model spectrum for Crab nebula emission and a calibration data set consisting of a number of spectra from the Crab and the on-board Am241 calibration source, uniformly covering a whole RXTE span. The new method led to a much more effective model convergence and allowed for better understanding of the behavior of the PCA energy-to-channel relationship. It greatly improved the response matrix performance. We describe the new version of the RXTE/PCA response generator PCARMF vll.7 along with the corresponding energy-to-channel conversion table (version e05v04) and their difference from the previous releases of PCA calibration. The new PCA response adequately represents the spectrum of the calibration sources and successfully predicts the energy of the narrow iron emission line in Cas-A throughout the RXTE mission.

  2. Surface Science Letters Effect of electromagnetic interactions on plasmon excitations in silver particle ensembles

    Microsoft Academic Search

    H.-M. Benia; N. Nilius; H.-J. Freund

    The optical properties of silver nano-particle ensembles are studied as a function of particle density by analyzing the light emission excited via electron injection from an STM tip. The particles are prepared with distinct dome and disk-like shapes on a Al2O3\\/NiAl(1 1 0) support. The particle density is varied over one order of magnitude by changing the Ag deposition temperature

  3. Life in the universe: foundation for exciting multidisciplinary science activities for middle and elementary school classes.

    PubMed

    Milne, D; O'Sullivan, K

    1994-01-01

    Young students find extra-terrestrial life one of the most intriguing of all topics. A project funded by the National Science Foundation and NASA, and administered by the SETI Institute, is underway to devise science lessons for grades 3-9 that draw upon this fascination. The lessons are designed by teachers and persons with long experience at curriculum design, tested in classrooms, revised and retested. Six guides, each containing some 6-10 science lessons, will be finished by summer, 1994. The theme Life in the Universe lends itself naturally to integrated treatment of facts and concepts from many scientific disciplines. The lessons for two completed guides span the origin of planet systems, evolution of complex life, chemical makeup of life, astronomy, spectroscopy, continental drift, mathematics and SETI (Search for Extra-Terrestrial Intelligence). All lessons are hands-on, interesting, and successful. PMID:11537956

  4. Life in the Universe: Foundation for exciting multidisciplinary science activities for middle and elementary school classes

    NASA Technical Reports Server (NTRS)

    Milne, D.; O'Sullivan, K.

    1994-01-01

    Young students find extra-terrestrial life one of the most intriguing of all topics. A project funded by the National Science Foundation and NASA, and administered by the SETI Institute, is underway to devise science lessons for grades 3-9 that draw upon this fascination. The lessons are designed by teachers and persons with long experience at curriculum design, tested in classrooms, revised and retested. Six guides, each containing some 6-10 science lessons, will be finished by summer, 1994.The theme Life in the Universe lends itself naturally to integrated treatment of facts and concepts from many scientific disciplines. The lessons for two completed guides span the origin of planet systems, evolution of complex life, chemical makeup of life, astronomy, spectroscopy, continental drift, mathematics and SETI (Search for Extra-Terrestrial Intelligence). All lessons are hands-on, interesting, and successful.

  5. Properties of X-ray binaries in the Magellanic Clouds from RXTE and Chandra observations

    NASA Astrophysics Data System (ADS)

    Corbet, R. H. D.; Coe, M. J.; McGowan, K. E.; Schurch, M. P. E.; Townsend, L. J.; Galache, J. L.; Marshall, F. E.

    2009-03-01

    The X-ray binary population of the SMC is very different from that of the Milky Way consisting, with one exception, entirely of transient pulsating Be/neutron star binaries. We have now been monitoring these SMC X-ray pulsars for over 10 years using the Rossi X-ray Timing Explorer with observations typically every week. The RXTE observations have been complemented with surveys made using the Chandra observatory. The RXTE observations are non-imaging but enable detailed studies of pulsing sources. In contrast, Chandra observations can provide precise source locations and detections of sources at lower flux levels, but do not provide the same timing information or the extended duration light curves that RXTE observations do. We summarize the results of these monitoring programs which provide insights into both the differences between the SMC and the Milky Way, and the details of the accretion processes in X-ray pulsars.

  6. "We use exciting, diverse methods to study Cognitive Science." carleton.ca/ics

    E-print Network

    Dawson, Jeff W.

    . Carleton offers a fully integrated cognitive science program. Our graduate programs bring together research and cognition to the design, implementation and evaluation of advanced human-machine systems n investigating in cognition, such as Statistics Canada, the Department of National Defence, the National Research Council

  7. RXTE/PCA and Swift/XRT observations of GRO J1655-40 during decay

    NASA Astrophysics Data System (ADS)

    Homan, Jeroen; Kong, Albert; Tomsick, John; Miller, Jon; Campana, Sergio; Wijnands, Rudy; Belloni, Tomaso; Lewin, Walter

    2005-10-01

    Following its transition to the hard state (ATels #607,#612), we have continued our daily RXTE/PCA observations of the black hole X-ray transient GRO J1655-40 (see http://tahti.mit.edu/opensource/1655). Between September 23, when the source reached the hard state, and October 10, the RXTE/ PCA count rate decreased exponentially, with an e-folding time of ~7 days. After October 10 the decrease started to slow down and data from the last few days suggest that the count rate may have reached a constant level.

  8. RXTE finds a new 723s pulsar in the SMC (SXP723)

    NASA Astrophysics Data System (ADS)

    Townsend, L. J.; Coe, M. J.; Corbet, R. H. D.; Galache, J. L.; Schurch, M. P. E.

    2011-08-01

    An RXTE observation performed as part of our long-term programme to monitor the SMC (see Galache et al., 2008, ApJS, 177, 189 for details) on 2011-06-20 (MJD 55732.22) has revealed highly significant (>4 sigma) pulsations at 723 ± 2s. This period was detected along with its 2nd and 3rd harmonics at 361.4s and 240.5s respectively. The pointing position of RXTE for the 11ks observation (ObsID: 96037-04-25) was RA = 12.5 degrees, dec = -73.1 degrees (J2000.0).

  9. / http://www.sciencemag.org/content/early/recent / 21 August 2014 / Page 1 / 10.1126/science.1253493 The dynamic response of magnetic order to ultrafast external excitation

    E-print Network

    Aeschlimann, Martin

    can directly switch magnetic domains in ferri- magnetic GdFeCo alloy films without an applied magnetic images of [Co(0.4 nm)/Pt(0.7)]N multilayers (N = 8, 5 and 3) which have perpendicular magnetic anisotropy.1126/science.1253493 The dynamic response of magnetic order to ultrafast external excitation is a fascinating

  10. X-ray periodicities in sources observed by the RXTE ASM

    E-print Network

    Shivamoggi, Vasudha B

    2005-01-01

    The X-ray intensities measured from 230 X-ray sources observed by the RXTE All-Sky Monitor (ASM) were analyzed for periodic behavior. The ASM has been observing sources for nine years in the 1.5-12 keV energy range. In ...

  11. RXTE observation of NGC 6240: a search for the obscured active nucleus

    E-print Network

    Yasushi Ikebe; Karen Leighly; Yasuo Tanaka; Takao Nakagawa; Yuichi Terashima; Stefanie Komossa

    2000-03-02

    The wide-band energy spectrum of NGC6240 over the range 0.5-200keV is investigated using the RXTE and ASCA data. The RXTE data provide the spectrum beyond the ASCA range (0.5-10 keV) with significant detection of signals up to 20keV and the upper limits above 20keV. The spectrum above 10keV is found to be very flat. A strong iron-K emission line discovered in the previous ASCA observation is also confirmed with the RXTE PCA. These results provide further evidence for the dominance of a reflection component, i.e. emission from cool material illuminated by an AGN. By fitting the spectra obtained with RXTE and ASCA simultaneously, we satisfactorily modeled the AGN spectrum with a Compton reflection component and probably a transmitted AGN component penetrating through a thick absorber. The X-ray luminosity of the AGN is estimated to be in the range 4x10^43 - 6x10^44 ergs/s in the range 2-10keV, which categorizes NGC6240 among the most luminous Seyfert nuclei. The ratio of the 2-10keV X-ray luminosity to the infrared luminosity, L_X(2-10keV)/L_IR, is 0.01 - 0.1, which implies a quite substantial, if not dominant, contribution of AGN to the infrared luminosity.

  12. Using the Unconventional Stellar Aspect (USA) and the Rossi X-ray Timing Explorer (RXTE) Experimental Data to Determine Atmospheric Composition, Density, and Temperature

    NASA Astrophysics Data System (ADS)

    Determan, J. R.; Budzein, S. A.; Titarchuk, L.

    2002-05-01

    The X-ray Astronomy Branch of the Naval Research Laboratory launched the Unconventional Stellar Aspect (USA) experiment aboard the Advanced Research and Global Observation Satellite (ARGOS) in 1999. USA is an X-ray timing experiment with a large collecting area and microsecond time resolution capable of conducting a broad program of studies of galactic X-ray binaries. USA consists of a collimated proportional counter X-ray telescope and two detectors with ~1000 cm2 effective area each, sensitive to photons in the 1-15 keV energy range. The Rossi X-ray Timing Explorer (RXTE) was launched on December 30, 1995 from NASA's Kennedy Space Center. The mission is managed and controlled by NASA's Goddard Space Flight Center (GSFC) in Greenbelt, Maryland. RXTE features unprecedented time resolution in combination with moderate spectral resolution to explore the variability of X-ray sources. Time scales from microseconds to months are covered in an instantaneous spectral range from 2 to 250 keV. We have developed a new technique to measure the composition and structure of the upper atmosphere using atmospheric occultation of celestial x-ray sources. Both USA and RXTE provide energy-resolved photon extinction curves, and the combined energy ranges of USA and RXTE permit direct probing of the mesosphere and lower thermosphere (80-160 km). Roughly speaking, differential absorption among energy bands can provide composition information, and the shape of the light curves total density versus altitude. Two complementary algorithms have been employed in the data analysis. The first method employs basis functions derived from NRLMSIS-00 (Picone et al 2000) in a Discrete Inverse Theory maximum likelihood retrieval of densities and temperature by fitting the light curve. The second method is a direct inversion of the light curve to determine optical depths and optical depth scale height, from which temperature and density may be iteratively derived in a self-consistent manner from NRLMSIS-00 composition information. The results from both methods are compared to each other, standard atmospheric models, and data from the High Resolution Airglow and Aurora Spectrograph (HIRAAS), mounted alongside USA on the ARGOS satellite. This research is the first to study the neutral atmosphere in this energy range, and complements UV airglow remote sensing techniques used aboard ARGOS that are less sensitive to nighttime neutral density. Enhanced Empirical Models of the Thermosphere, J. M. Picone, A. E.Hedin, D. P. Drob, R. R. Meier, J. Lean, A. C. Nicholas, and S. E. Thonnard, Physics and Chemistry of the Earth, Part C: Solar-Terrestrial and Planetary Science, 25(5-6), 537-42 (2000). Keywords: upper atmosphere, X-rays, horizon crossing, occultations

  13. News Conference: Brecon hosts 10th teacher's conference Summer school: Science summer school heads to Crete Award: The Corti Science Prize Radioactivity: Scottish beach is no beta off Workshop: Heureka project promotes teaching Experiments: Spanish project proves that learning science can be exciting Lecture: IOP schools lecture journeys from x-rays to antimatter Correction to the news item 'Delegates experience universality' Forthcoming events

    NASA Astrophysics Data System (ADS)

    2012-01-01

    Conference: Brecon hosts 10th teacher's conference Summer school: Science summer school heads to Crete Award: The Corti Science Prize Radioactivity: Scottish beach is no beta off Workshop: Heureka project promotes teaching Experiments: Spanish project proves that learning science can be exciting Lecture: IOP schools lecture journeys from x-rays to antimatter Correction to the news item 'Delegates experience universality' Forthcoming events

  14. International Observe the Moon Night - An Opportunity to Participate in the Year of the Solar System While Sharing the Excitement of Lunar Science and Exploration with the Public

    Microsoft Academic Search

    L. Bleacher; D. Daou; B. H. Day; B. C. Hsu; A. P. Jones; B. Mitchell; A. J. Shaner; S. S. Shipp

    2010-01-01

    International Observe the Moon Night (InOMN) is a multi-nation effort to share the excitement of recent lunar missions and new science results with education communities, amateur astronomers, space enthusiasts, and the general public. It is also intended to encourage the world to experience the thrill of observing Earth's closest neighbor. The inaugural InOMN took place on September 18, 2010. People

  15. CORONA, JET, AND RELATIVISTIC LINE MODELS FOR SUZAKU/RXTE/CHANDRA-HETG OBSERVATIONS OF THE CYGNUS X-1 HARD STATE

    E-print Network

    Nowak, Michael A.

    Using Suzaku and the Rossi X-ray Timing Explorer (RXTE), we have conducted a series of four simultaneous observations of the galactic black hole candidate Cyg X-1 in what were historically faint and spectrally hard "low ...

  16. RXTE timing and spectroscopy of a black hole X-ray binary in outburst

    NASA Technical Reports Server (NTRS)

    Miller, Jon; Swank, Jean (Technical Monitor)

    2005-01-01

    Under this program, RXTE observed the Galactic black hole candidate X-ray binary H1743-322. Observations were made simultaneously in the X-ray and radio bands with Chandra and the VLA, respectively. First results from this multi-wavelength study have been reported in two papers published in refereed journals, one focusing on timing results and the other focusing on spectroscopy. The timing studies revealed high frequency QPOs at approximately 180 Hz and 240 Hz, likely in a 2:3 frequency ratio as predicted by some models. The RXTE spectra were remarkable in that they showed no evidence of disk reflection or line emission, both of which are expected in black holes.

  17. Observation of Nonthermal Emission from the Supernova Remnant IC443 with RXTE

    NASA Technical Reports Server (NTRS)

    Sturner, S. J.; Keohane, J. W.; Reimer, O.

    2002-01-01

    In this paper we present analysis of X-ray spectra from the supernova remnant IC443 obtained using the PCA on RXTE. The spectra in the 3 - 20 keV band are well fit by a two-component model consisting of thermal and nonthermal components. We compare these results with recent results of other X-ray missions and discuss the need for a cut-off in the nonthermal spectrum. Recent Chandra and XMM-Newton observations suggest that much of the nonthermal emission from IC443 can be attributed to a pulsar wind nebula. We present the results of our search for periodic emission in the RXTE PCA data. We then discuss the origin o f the nonthermal component and its possible association with the unidentified EGRET source.

  18. Long-term studies of Z sources with hexte\\/rxte

    Microsoft Academic Search

    F. D. Amico; W. Heindl; R. Rothschild

    2002-01-01

    Using the High Energy X-Ray Timing Experiment (HEXTE) on-board the Rossi XRay Timing Explorer (RXTE) we perform a spectral study of the Z sources, with emphasis on the production of hard X-ray tails (HXT). Data from the Proportional Counter Array (PCA) were used to determine the position of the source in the Z diagram. We present current results of this

  19. Cryogenic exciter

    DOEpatents

    Bray, James William (Niskayuna, NY); Garces, Luis Jose (Niskayuna, NY)

    2012-03-13

    The disclosed technology is a cryogenic static exciter. The cryogenic static exciter is connected to a synchronous electric machine that has a field winding. The synchronous electric machine is cooled via a refrigerator or cryogen like liquid nitrogen. The static exciter is in communication with the field winding and is operating at ambient temperature. The static exciter receives cooling from a refrigerator or cryogen source, which may also service the synchronous machine, to selected areas of the static exciter and the cooling selectively reduces the operating temperature of the selected areas of the static exciter.

  20. ASCA and Radio/RXTE Observations of GX 339-4

    NASA Technical Reports Server (NTRS)

    Nowak, M. A.; Wilms, J.; Dove, J. B.; Fender, R. P.

    1999-01-01

    We have analyzed three separate archival Advanced Satellite for Cosmology and Astrophysics (ASCA) observations and eight separate Rossi X-ray Timing Explorer (RXTE) observations of the black hole candidate GX 339-4 in its low luminosity, spectrally hard state. Three of the RXTE observations were strictly simultaneous with 843 MHz and 8.3- 9.1 GHz radio observations. All data sets show evidence for an approximately 6.4 keV Fe line with equivalent widths approximately 20-100 eV. 'Reflection models' show a hardening of the RXTE spectra with decreasing X-ray flux; however, these models do not exhibit evidence of a correlation between the photon index of the incident power law flux and the solid angle subtended by the reflector. None of the models fit to the X-ray data, however, simultaneously explain the observed radio properties. We argue that the spatial extent of the observed radio emission is at least 0(10(exp 7 GM/c squared). Timing analysis reveals that all observations save one show evidence of a persistent f(qpo approximately equals 0.3 Hz quasi-periodic oscillations(quasi-periodic oscillations)). The broad band (10-3-102 Hz) power appears to be dominated by two independent processes that can be modeled as very broad Lorentzians with Q approximately less than 1. Similar to Cyg X-1, the hard photon variability is seen to lag the soft photon vaxiability with the lag time increasing with decreasing Fourier frequency. The magnitude of this time lag is seen to be positively correlated with the flux of GX 339-4.

  1. Anomalous X-ray Pulsars and Soft Gamma Repeaters as Magnetars: The RXTE Legacy

    NASA Astrophysics Data System (ADS)

    Kaspi, Victoria M.

    2012-01-01

    Prior to the launch of RXTE, the hypothesis by Thompson and Duncan that there exists a class of ultra-highly magnetized young neutron stars whose emission is powered by the decay of their magnetic field -- the so-called `magnetar' model -- was beautiful, yet unproven. The magnetar model was motivated the existence of Soft Gamma Repeaters (SGRs), which had been observed to exhibit dramatic X-ray and soft gamma ray bursts and in one case, 8-s pulsations in the tail of a major flare. Meanwhile, there was recognized another puzzling group of seemingly very different objects, the 'Anomalous X-ray Pulsars' (AXPs), so-called due to their bright, several-second X-ray pulsations, steady spin down, low spin-down power and absence of any binary companion from which mass could be accreted. AXPs had also been suggested to be magnetars by Thompson and Duncan, though this too was unproven. Today, thanks to multiple landmark RXTE results, these two groups of object have been united into a single source class, which is now nearly universally identified with magnetars. Specifically, the discovery from SGRs of regular X-ray pulsations and steady spin-down (as had been observed in AXPs), as well as the discovery of bright X-ray bursts from AXPs (as had been observed in SGRs) has demonstrated unambiguously the common nature of AXPs and SGRs, as was predicted uniquely in the magnetar model. Moreover, RXTE discoveries of several observational links between AXPs, SGRs and rotation-powered pulsars, specifically the detection of spin-up glitches in AXPs, as well as the observation of a temporary metamorphosis of one rotation-powered pulsar into a magnetar-like source, hint at a broader unification of the magnetars with the general radio pulsar population, with the observational differences attributable to a combination of age and magnetic field.

  2. RXTE all-sky slew survey. Catalog of X-ray sources at |b|>10o

    Microsoft Academic Search

    M. Revnivtsev; S. Sazonov; K. Jahoda; M. Gilfanov

    2004-01-01

    We report results of a serendipitous hard X-ray (3-20 keV), nearly all-sky (|b|>10o) survey based on RXTE\\/PCA observations performed during satellite reorientations in 1996-2002. The survey is 80% (90%) complete to a 4sigma limiting flux of ≈ 1.8 (2.5) × 10-11 erg s-1 cm-2 in the 3-20 keV band. The achieved sensitivity in the 3-8 keV and 8-20 keV subbands

  3. Quasi-periodic Oscillations Associated with Spectral Branches in RXTE Observations of Circinus X-1

    E-print Network

    Robert E. Shirey; Hale V. Bradt; Alan M. Levine; Edward H. Morgan

    1998-05-12

    We present Rossi X-ray Timing Explorer (RXTE) All-Sky Monitor observations of the X-ray binary Circinus X-1 which illustrate the variety of intensity profiles associated with the 16.55 d flaring cycle of the source. We also present eight observations of Cir X-1 made with the RXTE Proportional Counter Array over the course of a cycle wherein the average intensity of the flaring state decreased gradually over ~12 days. Fourier power density spectra for these observations show a narrow quasi-periodic oscillation (QPO) peak which shifts in frequency between 6.8 Hz and 32 Hz, as well as a broad QPO peak that remains roughly stationary at ~4 Hz. We identify these as Z-source horizontal and normal branch oscillations (HBOs/NBOs) respectively. Color-color and hardness-intensity diagrams (CDs/HIDs) show curvilinear tracks for each of the observations. The properties of the QPOs and very low frequency noise allow us to identify segments of these tracks with Z-source horizontal, normal, and flaring branches which shift location in the CDs and HIDs over the course of the 16.55 d cycle. These results contradict a previous prediction, based on the hypothesis that Cir X-1 is a high-Mdot atoll source, that HBOs should never occur in this source (Oosterbroek et al. 1995; van der Klis 1994).

  4. MULTIWAVELENGTH OBSERVATIONS OF LS I +61{sup 0} 303 WITH VERITAS, SWIFT, AND RXTE

    SciTech Connect

    Acciari, V. A. [Department of Life and Physical Sciences, Galway-Mayo Institute of Technology, Dublin Road, Galway (Ireland); Aliu, E. [Department of Physics and Astronomy and the Bartol Research Institute, University of Delaware, Newark, DE 19716 (United States); Arlen, T.; Chow, Y. C. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Bautista, M.; Cogan, P. [Physics Department, McGill University, Montreal, QC H3A 2T8 (Canada); Beilicke, M.; Bugaev, V. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Benbow, W. [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States); Boettcher, M. [Astrophysical Institute, Department of Physics and Astronomy, Ohio University, Athens, OH 45701 (United States); Bradbury, S. M.; Daniel, M. [School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Butt, Y.; Butt, Y. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Byrum, K. [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Cannon, A. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Cesarini, A. [School of Physics, National University of Ireland, Galway (Ireland); Ciupik, L. [Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States); Colin, P. [Physics Department, University of Utah, Salt Lake City, UT 84112 (United States); Cui, W. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States)], E-mail: awsmith@hep.anl.gov (and others)

    2009-08-01

    We present results from a long-term monitoring campaign on the TeV binary LSI +61{sup 0} 303 with VERITAS at energies above 500 GeV, and in the 2-10 keV hard X-ray bands with RXTE and Swift, sampling nine 26.5 day orbital cycles between 2006 September and 2008 February. The binary was observed by VERITAS to be variable, with all integrated observations resulting in a detection at the 8.8{sigma} (2006/2007) and 7.3{sigma} (2007/2008) significance level for emission above 500 GeV. The source was detected during active periods with flux values ranging from 5% to 20% of the Crab Nebula, varying over the course of a single orbital cycle. Additionally, the observations conducted in the 2007-2008 observing season show marginal evidence (at the 3.6{sigma} significance level) for TeV emission outside the apastron passage of the compact object around the Be star. Contemporaneous hard X-ray observations with RXTE and Swift show large variability with flux values typically varying between 0.5 and 3.0 x10{sup -11} erg cm{sup -2} s{sup -1} over a single orbital cycle. The contemporaneous X-ray and TeV data are examined and it is shown that the TeV sampling is not dense enough to detect a correlation between the two bands.

  5. Multiwavelength observations of LS I +61\\circ 303 with VERITAS, Swift and RXTE.

    SciTech Connect

    Byrum, K.; Smith, A. W.; Wagner, R. G; Acciari, V. A; Aliu, E.; Arlen, T.; Bautista, M.; Beilicke, M. (High Energy Physics); (Galway-Mayo Inst. of Tech.); (Univ. of Delaware); (Univ. of California); (McGill Univ.); (Washington Univ.)

    2009-04-01

    We present results from a long-term monitoring campaign on the TeV binary LSI +61{sup o} 303 with VERITAS at energies above 500 GeV, and in the 2-10 keV hard X-ray bands with RXTE and Swift, sampling nine 26.5 day orbital cycles between 2006 September and 2008 February. The binary was observed by VERITAS to be variable, with all integrated observations resulting in a detection at the 8.8{sigma} (2006/2007) and 7.3{sigma} (2007/2008) significance level for emission above 500 GeV. The source was detected during active periods with flux values ranging from 5% to 20% of the Crab Nebula, varying over the course of a single orbital cycle. Additionally, the observations conducted in the 2007-2008 observing season show marginal evidence (at the 3.6{sigma} significance level) for TeV emission outside the apastron passage of the compact object around the Be star. Contemporaneous hard X-ray observations with RXTE and Swift show large variability with flux values typically varying between 0.5 and 3.0 x 10{sup -11} erg cm{sup -2} s{sup -1} over a single orbital cycle. The contemporaneous X-ray and TeV data are examined and it is shown that the TeV sampling is not dense enough to detect a correlation between the two bands.

  6. Using Remote Sensing Technology, Web Casts, and Participation in a Valuable Research Project to Jazz Teachers and Excite Students About Science

    NASA Astrophysics Data System (ADS)

    Benko, T. M.; Czajkowski, K. P.; Struble, J.; Zhao, L.

    2002-12-01

    Scientific education of primary and secondary school children has become a topic of concern in Ohio and throughout the United States. So with that in mind, how do you get students excited about learning science? One route is to inform and jazz teachers about current technology! The University of Toledo has hosted three one-week, NASA and OhioView sponsored professional development institutes entitled, Observing Earth from Space, for teachers from grades K-12 during July 2000, 2001, and 2002. Sixty-seven teachers from the Upper Midwest and Kansas with Earth Science, Social Studies, and Physics backgrounds attended. Each participant acquired new ideas, plenty of educational materials, and posters of satellite imagery. The teachers received basic training in remote sensing, global positioning systems, digital elevation models, and weather observing techniques and learned about useful remote sensing applications. This instruction was conducted through: 1) presentations given by research scientists, 2) integration of the learned content into authentic, hands-on lesson plans, and 3) participation in a learning adventure, where their students collected real-time earth science data at their respective schools while university research scientists gathered corresponding satellite imagery. The students observations were submitted via a simple Web interface: www.remotesensing.utoledo.edu. One of the very exciting platforms used to communicate with the teachers and students throughout the school year were live Web Casts sponsored by NASA Glenn Research Center. The students data have successfully assisted in the validation of cloud/snow remote sensing algorithms, and next year the students observations will include various surface temperature readings. The participation in a cutting-edge technology workshop and in an important global climate change research project, applicable in the classroom, has added another worthwhile dimension to the learning process and career awareness for both the teachers and their students.

  7. Map, Excite, Jump, and Measure: An Outreach Activity That Utilizes Seismology to Engage Students in Technology, Science, Engineering, and Mathematics

    NASA Astrophysics Data System (ADS)

    van der Lee, S.; Tekverk, K.; Rooney, K.; Boxerman, J.

    2013-12-01

    We designed and will present a lesson plan to teach students STEM concepts through seismology. The plan addresses new generation science standards in the Framework for K-12 Science Education as well AAAS Benchmarks for Science Literacy. The plan can be executed at a facility with a seismometer in a research facility or university, on a field trip, but it can also be used in a school setting with a school seismometer. Within the lesson plan, the students first use technology to obtain earthquake location data and map them. Next, the students learn about the science of earthquakes, which is followed by an engineering activity in which the students design a hypothetical seismometer and interact with the actual seismometer and live data display. Lastly the students use mathematics to locate an earthquake through trilateration. The lesson plan has been fine-tuned through implementation with over 150 students from grades 3-12 from the Chicago area.

  8. Using Modern And Inexpensive Tools In the Classroom To Teach Spectroscopy And To Do Exciting Citizen Science On Astronomical Objects

    NASA Astrophysics Data System (ADS)

    Field, T.

    2014-12-01

    Spectroscopy is a key tool used in modern astronomical research. But, it's always been a difficult topic to teach or practice because the expense and complexity of the available tools. Over the past few years, there's been somewhat of a revolution in this field as new technologies have applied. In this presentation we'll review some new spectroscopy tools that enable educators, students and citizen scientists to do exciting spectroscopic work. With the addition of a simple, inexpensive grating, it's now possible to capture scientifically significant spectra of astronomical objects with small (6") telescopes and even just a DSLR. See the tools that citizen scientists are using to contribute data to pro-am collaborations around the world. We'll also examine a simple, surprisingly inexpensive, tripod-mounted spectrometer that can be used in the classroom for demonstrations and hands-on labs with gas tubes and other light sources. Both of the above instruments use a software program named RSpec, which is state of the art software suite that is easy to learn and easy to use. In this presentation we'll see these devices in operation and discuss how they can be used by educators to dramatically improve their teaching of this topic. You'll see how these tools can eliminate the frustration of hand-held rainbow foil and plastic spectrometers. And we'll review some exciting examples of astronomical spectra being collected by amateurs and educators.

  9. How to Use a Bed of Nails to Facilitate Excitement during a Science Road Show Presentation at Local Schools

    Microsoft Academic Search

    Fabian Pena; Shawn Kridler; Pete Berger

    2008-01-01

    The authors will demonstrate how to use a bed of nails to pump up the students at local K-12 schools. The use during Science Road Show presentations will be addressed along with suggestions on how to build the drama and introduce humor and learning.

  10. How to Use a Bed of Nails to Facilitate Excitement during a Science Road Show Presentation at Local Schools

    NASA Astrophysics Data System (ADS)

    Pena, Fabian; Kridler, Shawn; Berger, Pete

    2008-03-01

    The authors will demonstrate how to use a bed of nails to pump up the students at local K-12 schools. The use during Science Road Show presentations will be addressed along with suggestions on how to build the drama and introduce humor and learning.

  11. Simultaneous Rxte-Xmm Observations of GX339-4: a Galactic Seyfert 1?

    NASA Astrophysics Data System (ADS)

    Nowak, Michael

    GX339-4 is unique among persistent black hole candidates in that the emission is likely dominated by the accretion flow all the way from radio to gamma-ray wavelengths. Furthermore, as we and others have recently shown with a series of multiwavelength observations, there are strong correlations among these energy bands that pose serious challenges for models of: advection dominated accretion flows (ADAF/ADIOS), reprocessing of the X-rays by the accretion disk, coronal flare-induced variability, etc. We propose a series of 5 simultaneous RXTE-XMM observations (with accompanying ground-based IR/optical and radio whenever possible) that will allow us to probe the optical to EUV to hard X-ray energy bands.

  12. RXTE Observations of 1A 1744-361: Correlated Spectral and Timing Behavior

    E-print Network

    Sudip Bhattacharyya; Tod E. Strohmayer; Jean H. Swank; Craig B. Markwardt

    2006-07-20

    We analyze Rossi X-ray Timing Explorer (RXTE) Proportional Counter Array (PCA) data of the transient low mass X-ray binary (LMXB) system 1A 1744-361. We explore the X-ray intensity and spectral evolution of the source, perform timing analysis, and find that 1A 1744-361 shows `atoll' behavior during the outbursts. The color-color diagram indicates that this LMXB was observed in a low intensity spectrally hard (low-hard) state and in a high intensity `banana' state. The low-hard state shows a horizontal pattern in the color-color diagram, and the previously reported `dipper QPO' appears only during this state. We also perform energy spectral analyses, and report the first detection of broad iron emission line and iron absorption edge from 1A 1744-361.

  13. Probing Dense Matter in the cores of AGN: Observations with RXTE and ASCA

    E-print Network

    K. A. Weaver

    2000-07-21

    Preliminary results from an X-ray spectral study of Seyfert 1 galaxies with ASCA and RXTE are presented. From an analysis of X-ray reprocessing features of Compton reflection and Fe K-alpha fluorescence, it is found that iron line strength is not necessarily a good predictor of the amount of reflection. The variability properties of Fe K-alpha and reflection do not necessarily scale together and substantial decoupling of the behavior of the reprocessed flux with respect to continuum variability is common. Such trends suggest the presence of multiple and/or complex regions of dense matter in AGN cores and that standard accretion disk models drastically oversimplify reality.

  14. X-ray Transients Monitored by the All-Sky Monitor on RXTE: A Tabulation

    E-print Network

    Hale Bradt; Alan Levine; Ronald Remillard; Donald A. Smith

    2000-03-30

    We present a tabulation of 46 transient x-ray sources monitored with the All-Sky Monitor (ASM) on the Rossi X-ray Timing Explorer (RXTE). They fall into four broad categories: short (~d), intermediate, and long (>500 d) duration of outbursts, and long period binary systems that flare up at periastron (e.g., Be systems). The mixture of outburst/quiescent cycles and low-level persistent emission in a few systems could indicate conditions are near the limit for stable mass flow in the accretion disk. The two short-time-scale systems, CI Cam and V4641 Sgr, are within 1 kpc of the sun, and hence many more such systems may await discovery.

  15. RXTE All-Sky Monitor Localization of SGR 1627-41

    E-print Network

    Donald A. Smith; Hale V. Bradt; Alan M. Levine

    1999-05-12

    The fourth unambiguously identified Soft Gamma Repeater (SGR), SGR1627-41, was discovered with the BATSE instrument on 1998 June 15 (Kouveliotou et al. 1998). Interplanetary Network (IPN) measurements and BATSE data constrained the location of this new SGR to a 6 deg segment of a narrow (19") annulus (Hurley et al. 1999; Woods et al. 1998). We present two bursts from this source observed by the All-Sky Monitor (ASM) on RXTE. We use the ASM data to further constrain the source location to a 5' long segment of the BATSE/IPN error box. The ASM/IPN error box lies within 0.3' of the supernova remnant (SNR) G337.0-0.1. The probability that a SNR would fall so close to the error box purely by chance is ~5%.

  16. RXTE Discovery of the Spin Period of Swift J1834.9-0846

    NASA Astrophysics Data System (ADS)

    Gogus, Ersin; Kouveliotou, Chryssa

    2011-08-01

    RXTE/PCA observed the new source, Swift J1834.9-0846 (D'Elia et al. GCN Circ. 12253, Guiriec et al. 12255) on 2011 August 9-10, for a net exposure time of 9.7 ks. We performed a timing analysis using the barycentered photon arrival times in the 2-10 keV band and detected a coherent pulsation at 0.402853(2) Hz which corresponds to a spin period of 2.482295 s. Note that an earlier PCA observation on 2011 August 9 of the same field with a 3.4 ks exposure did not reveal the pulsed signal clearly but it does confirm the signal at a consistent frequency.

  17. The Broadband Continuum Spectrum of Magnetar Bursts from Swift and RXTE

    NASA Astrophysics Data System (ADS)

    Ibrahim, Alaa

    We studied a large number of SGR bursts with Swift and RXTE to determine the best fit continuum model in the broad range of 2-350 keV. Using 10 trial models, we find acceptable fits with single component Optically thin thermal Bremsstarahlung, Cutoff Power-law, and simple Power-law models that rule out the need for a second component. We present the global spectral properties of the bursts and investigation spectral-temporal correlations. (*) This contribution presents results from students projects carried out during the 8th COSPAR Capacity Building Workshop on Space Astrophysics with NASA & ESA Missions: Swift, Chandra & XMM Newton (Jan. 20-Feb. 2, 2008; Alexandria, Egypt; http://cais.cu.edu.eg/astro)

  18. Rms-flux relation of Cyg X-1 with RXTE: dipping and nondipping cases

    E-print Network

    Y. J. Lei; L. M. Song; J. L. Qu; C. M. Zhang

    2007-06-01

    The rms (root mean square) variability is the parameter for understanding the emission temporal properties of X-ray binaries (XRBs) and active galactic nuclei (AGN). The rms-flux relation with Rossi X-ray Timing Explorer (RXTE) data for the dips and nondip of black hole Cyg X-1 has been investigated in this paper. Our results show that there exist the linear rms-flux relations in the frequency range 0.1-10 Hz for the dipping light curve. Moreover, this linear relation still remains during the nondip regime, but with the steeper slope than that of the dipping case in the low energy band. For the high energy band, the slopes of the dipping and nondipping cases are hardly constant within errors. The explanations of the results have been made by means of the ``Propagating Perturbation'' model of Lyubarskii (1997).

  19. A DOUBLE-PEAKED OUTBURST OF A 0535+26 OBSERVED WITH INTEGRAL, RXTE, AND SUZAKU

    SciTech Connect

    Caballero, I. [Laboratoire AIM, CEA/IRFU, CNRS/INSU, Universite Paris Diderot, CEA DSM/IRFU/SAp, F-91191 Gif-sur-Yvette (France); Pottschmidt, K.; Marcu, D. M. [Center for Space Science and Technology, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States); Barragan, L.; Wilms, J.; Kreykenbohm, I. [Dr. Karl Remeis-Sternwarte and ECAP, FAU Erlangen-Nuremberg, Sternwartstr. 7, D-96049 Bamberg (Germany); Ferrigno, C. [ISDC Data Centre for Astrophysics, University of Geneva, Chemin d'Ecogia 16, CH-1290 Versoix (Switzerland); Klochkov, D.; Suchy, S.; Santangelo, A.; Staubert, R. [Institut fuer Astronomie und Astrophysik, Sand 1, D-72076 Tuebingen (Germany); Zurita Heras, J. A. [Francois Arago Centre, APC (UMR 7164 Universite Paris Diderot, CNRS/IN2P3, CEA/DSM, Observatoire de Paris), 13 rue Watt, F-75205 Paris Cedex 13 (France); Kretschmar, P. [European Space Astronomy Centre (ESA/ESAC), Science Operations Department, Villanueva de la Canada, E-28080 Madrid (Spain); Fuerst, F. [Space Radiation Lab, California Institute of Technology, MC 290-17 Cahill, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Rothschild, R. [Center for Astrophysics and Space Science, UCSD, La Jolla, CA 92093 (United States); Finger, M. H. [National Space Science and Technology Center, 320 Sparkman Drive NW, Huntsville, AL 35805 (United States); Camero-Arranz, A. [Institut de Ciencies de l'Espai (IEEC-CSIC), Campus UAB, Fac. de Ciencies, Torre C5, parell, 2a planta, E-08193 Barcelona (Spain); Makishima, K. [Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan); Enoto, T. [Cosmic Radiation Laboratory, RIKEN, 2-1, Hirosawa, Wako City, Saitama 351-0198 (Japan); Iwakiri, W., E-mail: isabel.caballero@cea.fr [Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura, Saitama 338-8570 (Japan); and others

    2013-02-20

    The Be/X-ray binary A 0535+26 showed a normal (type I) outburst in 2009 August. It is the fourth in a series of normal outbursts associated with the periastron, but is unusual because it presented a double-peaked light curve. The two peaks reached a flux of {approx}450 mCrab in the 15-50 keV range. We present results of the timing and spectral analysis of INTEGRAL, RXTE, and Suzaku observations of the outburst. The energy-dependent pulse profiles and their evolution during the outburst are studied. No significant differences with respect to other normal outbursts are observed. The centroid energy of the fundamental cyclotron line shows no significant variation during the outburst. A spectral hardening with increasing luminosity is observed. We conclude that the source is accreting in the sub-critical regime. We discuss possible explanations for the double-peaked outburst.

  20. RXTE/HEXTE Analysis of the Crab Pulsar Glitch of July 2000

    NASA Astrophysics Data System (ADS)

    Vivekanand, M.

    2015-06-01

    Hard X-ray data from the RXTE observatory (HEXTE energy range 15–240 keV) have been analyzed to obtain a phase-coherent timing solution for the Crab pulsar glitch of 2000 July 15. The results are: (1) the step change in the rotation frequency {? }0 of the Crab pulsar at the epoch of the glitch is ? {? }0 =\\(30+/- 3)× {10}-9× {? }0; (2) the step change in its time derivative is ? {\\stackrel{\\dot{}}{? }}0=(4.8+/- 0.6)× {10}-3× {\\stackrel{\\dot{}}{? }}0; and (3) the timescale of decay of the step change is {? }d =\\4.7+/- 0.5 days. The first two results are consistent with those obtained at radio frequencies by the Jodrell Bank observatory. The last result has not been quoted in the literature, but could be an underestimate due to a lack of observations very close to the glitch epoch. Through comparison with the monthly timing ephemeris published by the Jodrell group for the Crab pulsar, the time delay between the main peaks of the hard X-ray and radio pulse profiles is estimated to be +411 ± 167 ?s. Although this number is not very significant, it is consistent with the number derived for the 2–16 keV energy range, using the Proportional Counter Array instrument of RXTE. The separation between the two peaks of the integrated pulse profile of the Crab pulsar and the ratio of their intensities are both statistically similar before and after the glitch. The dead time corrected integrated photon flux within the integrated pulse profile appears to decrease after the glitch, although this is not a statistically strong result. This work achieves what can be considered to be an almost absolute timing analysis of the Crab pulsar hard X-ray data.

  1. Focus Issue: Getting Excited About Glia

    NSDL National Science Digital Library

    Elizabeth M. Adler (American Association for the Advancement of Science; Science Signaling REV)

    2010-11-09

    This Focus Issue of Science Signaling complements the Science Special Issue and highlights glial cell function, development, and disease. This issue draws attention to the molecular mechanisms of drug resistance of a cancer of glial origin, and to signaling between glia and neurons. Although glia may not be excitable, they are clearly an exciting group of cells.

  2. RXTE observations of GS 1354-644 recurrent X-ray Nova outburst

    E-print Network

    Revnivtsev, M G; Priedhorsky, W C; Vikhlinin, A A; Revnivtsev, Mikhail G; Borozdin, Konstantin N.; Priedhorsky, William C.; Vikhlinin, Alexey

    1999-01-01

    We present the results of Rossi X-ray Timing Explorer observations of GS 1354-644 during its 1997--1998 modest outburst.The source is one of a few black hole X-ray transients, which is confirmed to be recurrent, i.e. more than one X-ray outburst was detected. Previous outburst of the same source observed with Ginga in 1987 was much brighter, and the source was found in high/soft spectral state. In 1997-1998 GS1354-644 was clearly in another typical for black hole binaries spectral state - hard/low. Total duration of the outburst was 150-200 days in RXTE/ASM band. PCA and HEXTE observations cover $\\sim$70 days close to the maximum of the light curve and during the flux decline. The overall power-law like spectrum shape almost did not change during the observations and can be approximated by models of up-scattering of soft photons by energetic electrons in a hot plasma cloud with the temperature kT ~30 keV and optical depth \\tau~4-5(for spherical geometry). For good fit of the data an addition of an iron fluore...

  3. Constraints on RRAT Emission Mechanisms from RXTE/PCA Observations of RRAT J1819-1458

    E-print Network

    Robert E. Rutledge

    2006-09-07

    We derive the second and most stringent limit to date of the X-ray/radio flux ratio (F_x/F_R) for the radio bursts associated with the recently identified source class, the Rotating Radio Transients (RRATs). We analyze 20.1 hr of \\rxte/PCA observations of RRAT J1819-1458 -- a period during which 350\\ppm23 RRAT radio bursts occurred, based on the previously observed average radio burst rate. No X-ray bursts were detected, implying an upper-limit on the X-ray flux for RRAT-bursts of burst flux is bursts from the RRAT are energetically unimportant compared with the persistent X-ray emission. From the previously observed burst radio flux, we derive an upper-limit F_x/F_Rbursts from this RRAT, the most stringent to date, due to the high radio flux of bursts from this source. The F_x/F_R ratio is a factor approximately 80 larger than that of the millisecond pulsar PSR B1821-24; thus emission processes of X-ray/radio efficiency comparable to MSP pulses cannot be ruled out. However, if the RRAT burst emission mechanism is identical to the msec bursts of magnetars, then the msec bursts of magnetars should be easily detected with radio instrumentation; yet none have been reported to date.

  4. Observation of Kilohertz Quasiperiodic Oscillations from the Atoll Source 4U 1702-429 by RXTE

    NASA Technical Reports Server (NTRS)

    Markwardt, C. B.; Strohmayer, Tod E.; Swank, Jean H.

    1998-01-01

    We present results of Rossi X-Ray Timing Explorer (RXTE) observations of the atoll source 4U 1702-429 in the middle of its luminosity range. Kilohertz-range quasiperiodic oscillations (QPOS) were observed first as a narrow (FWHM approximately 7 Hz) peak near 900 Hz, and later as a pair consisting of a narrow peak in the range 625 825 Hz and a faint broad (FWHM 91 Hz) peak. When the two peaks appeared simultaneously the separation was 333 +/- 5 Hz. Six type I thermonuclear bursts were detected, of which five exhibited almost coherent oscillations near 330 Hz, which makes 4U 1702-429 only the second source to show burst oscillations very close to the kilohertz QPO separation frequency. The energy spectrum and color-color diagram indicate that the source executed variations in the range between the "island" and "lower banana" atoll states. In addition to the kilohertz variability, oscillations at approximately 10, approximately 35, and 80 Hz were also detected at various times, superimposed on a red noise continuum. The centroid of the approximately 35 Hz QPO tracks the frequency of the kilohertz oscillation when they were both present. A Lense-Thirring gravitomagnetic precession interpretation appears more plausible in this case, compared to other atoll sources with low frequency QPOs.

  5. Orbital Phase Spectroscopy of GX 301--2 with RXTE-PCA

    E-print Network

    U. Mukherjee; B. Paul

    2004-09-02

    We have investigated the orbital phase dependence of the X-ray spectrum of the High Mass X-ray Binary pulsar GX 301--2. Here we present the results from a spectral analysis of two sets of observations of GX 301--2 with the Rossi X-ray Timing Explorer (RXTE). Of particular interest are the variations of the absorption column density and the iron line flux along with other parameters of the spectral model with the orbital phase. We found that the X-ray spectrum can almost always be fitted with a partial covering absorption model. We have detected enhanced absorption near the periastron. However, the column density variation with orbital phase is not smooth, as is expected in a smooth stellar wind model. We discuss the results of the column density variation in the light of the two proposed models for GX 301-2, an equatorial disk emanating from the companion star Wray 977 and a gas stream following the neutron star. We also found that the iron K_alpha and K_beta line fluxes have peaks near the periastron and are well correlated with the continuum hard X-ray flux. The line equivalent width shows an interesting pattern with the column density, reasonably constant for low values of the column density and increasing rapidly beyond a certain value.

  6. Excited Delirium

    PubMed Central

    Takeuchi, Asia; Ahern, Terence L.; Henderson, Sean O.

    2011-01-01

    Excited (or agitated) delirium is characterized by agitation, aggression, acute distress and sudden death, often in the pre-hospital care setting. It is typically associated with the use of drugs that alter dopamine processing, hyperthermia, and, most notably, sometimes with death of the affected person in the custody of law enforcement. Subjects typically die from cardiopulmonary arrest, although the cause is debated. Unfortunately an adequate treatment plan has yet to be established, in part due to the fact that most patients die before hospital arrival. While there is still much to be discovered about the pathophysiology and treatment, it is hoped that this extensive review will provide both police and medical personnel with the information necessary to recognize and respond appropriately to excited delirium. PMID:21691475

  7. RXTE Observations of an Outburst of Recurrent X-ray Nova GS 1354-644

    E-print Network

    Mikhail G. Revnivtsev; Konstantin N. Borozdin; William C. Priedhorsky; Alexey Vikhlinin

    1999-10-13

    We present the results of Rossi X-ray Timing Explorer observations of GS 1354-644 during a modest outburst in 1997-1998. The source is one of a handful of black hole X-ray transients that are confirmed to be recurrent in X-rays. A 1987 outburst of the same source observed by Ginga was much brighter, and showed a high/soft spectral state. In contrast the 1997-1998 outburst showed a low/hard spectral state. Both states are typical for black hole binaries. The RXTE All Sky Monitor observed an outburst duration of 150 to 200 days. PCA and HEXTE observations covered ~70 days near the maximum of the light curve and during the flux decline. Throughout the observations, the spectrum can be approximated by Compton upscattering of soft photons by energetic electrons. The hot electron cloud has a temperature kT ~30 keV and optical depth tau~4--5. To fit the data well an additional iron fluorescent line and reflection component are required, which indicates the presence of optically thick cool material, most probably in the outer part of the accretion disk. Dramatic fast variability was observed, and has been analyzed in the context of a shot noise model. The spectrum appeared to be softest at the peaks of the shot-noise variability. The shape of the power spectrum was typical for black hole systems in a low/hard state. We note a qualitative difference in the shape of the dependence of fractional variability on energy, when we compare systems with black holes and with neutron stars. Since it is difficult to discriminate these systems on spectral grounds, at least in their low/hard states, this new difference might be important.

  8. An Expanded RXTE Survey of Long-Term X-ray Variability in Seyfert 1 Galaxies

    NASA Technical Reports Server (NTRS)

    Markowitz, A.; Edelson, R.

    2004-01-01

    The first seven years of RXTE monitoring of Seyfert 1 active galactic nuclei have been systematically analyzed to yield five homogenous samples of 2-12 keV light curves, probing hard X-ray variability on successively longer durations from approx. 1 day to approx. 3.5 years. 2-10 keV variability on time scales of approx. 1 day, as probed by ASCA, are included. All sources exhibit stronger X-ray variability towards longer time scales, with variability amplitudes saturating at the longest time scales, but the increase is greater for relatively higher luminosity sources. The well-documented anticorrelation between variability amplitude and luminosity is confirmed on all time scales. However, anticorrelations between variability amplitude and black hole mass estimate are evident on only the shortest time scales probed. The data are consistent with the models of power spectral density (PSD) movement described in Markowitz et al. (2003) and McHardy et al. (2004), whereby Seyfert 1 galaxies variability can be described by a single, universal PSD shape whose cutoff frequency scales with black hole mass. The best-fitting scaling relations between variability time scale, black hole mass and X-ray luminosity support an average accretion rate of 2% of the Eddington limit for the sample. Nearly all sources exhibit stronger variability in the relatively soft 2-4 keV band compared to the 7-12 keV band on all time scales. Color-flux diagrams support also Seyfert 1s' softening as they brighten. There are indications that relatively less luminous or less massive sources exhibit a greater degree of spectral variability for a given increase in overall flux.

  9. RXTE Observations of the Seyfert 2 Galaxy MrK 348

    NASA Technical Reports Server (NTRS)

    Smith, David A.; Georgantopoulos, Ioannis; Warwick, Robert S.

    2000-01-01

    We present RXTE monitoring observations of the Seyfert 2 galaxy Mrk 348 spanning a 6 month period. The time-averaged spectrum in the 3-20 keV band shows many features characteristic of a Compton-thin Seyfert 2 galaxy, namely a hard underlying power-law continuum (Gamma approximately equal 1.8) with heavy soft X-ray absorption (N(sub H) approximately 10(exp 23)/sq cm) plus measurable iron K.alpha emission (equivalent width approximately 100 eV) and, at high energy, evidence for a reflection component (R approximately < 1). During the first half of the monitoring period the X-ray continuum flux from Mrk 348 remained relatively steady. However this was followed by a significant brightening of the source (by roughly a factor of 4) with the fastest change corresponding to a doubling of its X-ray flux on a timescale of about 20 days. The flux increase was accompanied by a marked softening of X-ray spectrum most likely attributable to a factor approximately 3 decline in the intrinsic line-of-sight column density. In contrast the iron K.alpha line and the reflection components showed no evidence of variability. These observations suggest a scenario in which the central X-ray source is surrounded by a patchy distribution of absorbing material located within about a light-week of the nucleus of Mrk 348. The random movement of individual clouds within the absorbing screen, across our line of sight, produces substantial temporal variations in the measured column density on timescales of weeks to months and gives rise to the observed X-ray spectral variability. However, as viewed from the nucleus the global coverage and typical thickness of the cloud layer remains relatively constant.

  10. Results of WEBT, VLBA and RXTE monitoring of 3C 279 during 2006-2007

    E-print Network

    V. M. Larionov; S. G. Jorstad; A. P. Marscher; C. M. Raiteri; M. Villata

    2008-10-23

    We present radio-to-optical data taken by the WEBT, supplemented by VLBA and RXTE observations, of 3C 279. Our goal is to use this extensive database to draw inferences regarding the physics of the relativistic jet. We assemble multifrequency light curves with data from 30 ground-based observatories and the space-based instruments, along with linear polarization vs. time in the optical R band. In addition, we present a sequence of 22 images (with polarization vectors) at 43 GHz at resolution 0.15 milliarcsec, obtained with the VLBA. We analyse the light curves and polarization, as well as the spectral energy distributions at different epochs, corresponding to different brightness states. The IR-optical-UV continuum spectrum of the variable component corresponds to a power law with a constant slope of -1.6, while in the 2.4-10 keV X-ray band it varies in slope from -1.1 to -1.6. The steepest X-ray spectrum occurs at a flux minimum. During a decline in flux from maximum in late 2006, the optical and 43 GHz core polarization vectors rotate by ~300 degrees. The continuum spectrum agrees with steady injection of relativistic electrons with a power-law energy distribution of slope -3.2 that is steepened to -4.2 at high energies by radiative losses. The X-ray emission at flux minimum comes most likely from a new component that starts in an upstream section of the jet where inverse Compton scattering of seed photons from outside the jet is important. The rotation of the polarization vector implies that the jet contains a helical magnetic field that extends ~20 pc past the 43 GHz core.

  11. Attention STEM Teachers! Learn some exciting, simple, low-cost

    E-print Network

    Hochberg, Michael

    be integrated into your existing lesson plans. Why: To engage and excite young people in science and math! ogramAttention STEM Teachers! Learn some exciting, simple, low-cost experiments to engage your students

  12. employment opportunities in exciting career paths

    E-print Network

    Barthelat, Francois

    IN FOOD SCIENCE McGillMcGillMcGILL UNIVERSITY Photos: © USDA. Used with permission Design © 2006/03 HCR) 398-7977 e-mail: foodscience@mcgill.ca We are also on the web: www.mcgill.ca/foodscience/ McGill Food in exciting career paths Food Science Cerificate for BSc graduates Food Science Cerificate for BSc graduates

  13. Evolution of the orbital period of Her X-1: Determination of a new ephemeris using RXTE data

    NASA Astrophysics Data System (ADS)

    Stelzer, B.; Staubert, R.; Wilms, J.; Geckeler, R. D.; Gruber, D.; Rothschild, R.

    1997-05-01

    Her X-1 was observed by RXTE in July 1996 during the MAIN HIGH state of its 35 day cycle. Using data from the Proportional Counter Array (PCA) we redetermine the orbital parameters of the binary system. The analysis based on pulse-timing measurements yields new estimates for the orbital elements and an accurate spin period for the time of observation. By comparing our results with previous observations of Her X-1 we are able to report a new orbital ephemeris including an improved value for the decrease in orbital period.

  14. Multi-photon excitation microscopy

    Microsoft Academic Search

    Alberto Diaspro; Paolo Bianchini; Giuseppe Vicidomini; Mario Faretta; Paola Ramoino; Cesare Usai

    2006-01-01

    Multi-photon excitation (MPE) microscopy plays a growing role among microscopical techniques utilized for studying biological matter. In conjunction with confocal microscopy it can be considered the imaging workhorse of life science laboratories. Its roots can be found in a fundamental work written by Maria Goeppert Mayer more than 70 years ago. Nowadays, 2PE and MPE microscopes are expected to increase

  15. Food Science.

    ERIC Educational Resources Information Center

    Barkman, Susan J.

    1996-01-01

    Presents food science experiments designed for high school science classes that aim at getting students excited about science and providing them with real-life applications. Enables students to see the application of chemistry, microbiology, engineering, and other basic and applied sciences to the production, processing, preservation, evaluation,…

  16. RXTE and BeppoSAX Observations of MCG-5-23-16: Reflection From Distant Cold Material

    NASA Technical Reports Server (NTRS)

    Mattson, B. J.; Weaver, K. A.

    2003-01-01

    We examine the spectral variability of the Seyfert 1.9 galaxy MCG-5-23-16 using RXTE and BeppoSAX observations spanning 2 years from April 1996 to April 1998. During the first year the X-ray source brightens by a factor of approximately 25% on timescales of days to months. During this time, the reprocessed continuum emission seen with RXTE does not respond measurably to the continuum increase. However, by the end of the second year during the BeppoSAX epoch the X-ray source has faded again. This time, the reprocessed emission has also faded, indicating that the reprocessed flux has responded to the continuum. If these effects are caused by time delays due to the distance between the X-ray source and the reprocessing region, we derive a light crossing time of between approximately 1 light day and approximately 1.5 light years. This corresponds to a distance of 0.001 pc to 0.55 pc, which implies that the reprocessed emission originates between 3 x 10(exp 15) cm and 1.6 x 10(exp l8) cm from the X-ray source. In other words, the reprocessing in MCG-5-23-16 is not dominated by the inner regions of a standard accretion disk.

  17. Experience Gained From Launch and Early Orbit Support of the Rossi X-Ray Timing Explorer (RXTE)

    NASA Technical Reports Server (NTRS)

    Fink, D. R.; Chapman, K. B.; Davis, W. S.; Hashmall, J. A.; Shulman, S. E.; Underwood, S. C.; Zsoldos, J. M.; Harman, R. R.

    1996-01-01

    this paper reports the results to date of early mission support provided by the personnel of the Goddard Space Flight Center Flight Dynamics Division (FDD) for the Rossi X-Ray Timing Explorer (RXTE) spacecraft. For this mission, the FDD supports onboard attitude determination and ephemeris propagation by supplying ground-based orbit and attitude solutions and calibration results. The first phase of that support was to provide launch window analyses. As the launch window was determined, acquisition attitudes were calculated and calibration slews were planned. postlaunch, these slews provided the basis for ground determined calibration. Ground determined calibration results are used to improve the accuracy of onboard solutions. The FDD is applying new calibration tools designed to facilitate use of the simultaneous, high-accuracy star observations from the two RXTE star trackers for ground attitude determination and calibration. An evaluation of the performance of these tools is presented. The FDD provides updates to the onboard star catalog based on preflight analysis and analysis of flight data. The in-flight results of the mission support in each area are summarized and compared with pre-mission expectations.

  18. Particle Beam Excitation Electron Beam Excitation

    E-print Network

    Schroder, Dieter K.

    Microprobe Microanalysis (EMP) Transmission Electron Microscopy (TEM) Scanning Auger Microscopy (SAMParticle Beam Excitation Electron Beam Excitation Scanning Electron Microscopy (SEM) Electron Projector lens Electron multiplier Fluorescent screen X-Y stage Microchannel plate Immersion lens Measures m

  19. Disk-dominated States of 4U 1957+11: Chandra, XMM-Newton, and RXTE Observations of Ostensibly the Most Rapidly Spinning Galactic Black Hole

    E-print Network

    Nowak, Michael A.

    We present simultaneous Chandra High-Energy Transmission Gratings (HETG) and Rossi X-ray Timing Explorer (RXTE) observations of a "soft state" of the black hole candidate 4U 1957+11. These spectra, having limited hard X-ray ...

  20. Transient X--Ray Sources Observed with the Rxte All-Sky Monitor after 3.5 Years

    E-print Network

    Hale Bradt; Alan M. Levine; Ronald A. Remillard; Donald A. Smith

    2000-01-26

    We present light curves of a sample of "transient" sources observed with the All-Sky Monitor (ASM) of the Rossi X-ray Timing Explorer (RXTE). The light curves extend over 3.5 years. They are presented in three groups: six neutron-star systems, eight black-hole-candidate systems, and an additional diverse set of six objects that are either transient sources (in the sense of usually being undetectable) or persistent sources showing transient behavior. The outburst profiles of these sources show reproducible characteristics within one source and from source to source, as well as large variations. These profiles together with the profiles of the hardness ratios from the ASM are a valuable resource for the understanding of accretion instabilities. We summarize briefly some recent work by observers on these somewhat arbitrarily selected sources.

  1. Comprehensive Analysis of RXTE Data from Cyg X-1: Spectral Index-Quasi-Periodic Oscillation Frequency-Luminosity Correlations

    E-print Network

    Nickolai Shaposhnikov; Lev Titarchuk

    2006-02-04

    We present timing and spectral analysis of ~ 2.2 Ms of RXTE archival data from Cyg X-1. Using a generic Comptonization model we reveal that the spectrum of Cyg X-1 consists of three components: a thermal seed photon spectrum, a Comptonized part of the seed photon spectrum and the iron line. We find a strong correlation between the 0.1-20 Hz frequencies of quasiperiodic oscillations (QPOs) and the spectral index. Presence of two spectral phases (states) are clearly seen in the data when the spectral indices saturate at low and high values of QPO frequencies. This saturation effect was discovered earlier in a number of black hole candidate (BHC) sources and now we strongly confirm this phenomenon in Cyg X-1. In the soft state this index-QPO frequency correlation shows a saturation of the photon index Gamma ~ 2.1 at high values of the low frequency \

  2. Materials modification by electronic excitation

    NASA Astrophysics Data System (ADS)

    Stoneham, A. M.; Itoh, Noriaki

    2000-12-01

    Electronic excitation by lasers or electron beams can modify the properties of materials. The changes are not just due to heat, nor do they result from the well-known collision dynamics of much radiation damage. Everyday examples of modification by electronic excitation include photography, and photochromics (such as sunglasses) which change colour. In the last few years it has become clear that excitation can offer novel types of modification, with better-controlled changes. The field has evolved through a mix of basic science, of new laser and electron beam tools, and of new needs from microelectronics, photonics and nanotechnology. Underlying this development are some common themes which integrate the basic science and its applications. These include especially the ideas of energy localisation and charge localisation. There are detailed comparisons of experiment and theory for halides, but there is a wealth of information for other materials. From this, we identify ways to connect understanding to technological needs, like selective removal of material, controlled changes, altering the balance between process steps, and possibilities of quantum control. The field is reviewed in full in our recent book [N. Itoh, A.M. Stoneham, Materials Modification by Electronic Excitation, Cambridge University Press, Cambridge, 2000].

  3. Absolute Cross Sections(Supported by Office of Fusion Energy Sciences, U.S. Dept. of Energy) for Electron Impact Excitation of B^2+ and C^3+

    Microsoft Academic Search

    O. Woitke; Y.-S. Chung; N. Djuric; B. Wallbank; S. Zhou; G. H. Dunn; M. E. Bannister; A. C. H. Smith

    1998-01-01

    Absolute cross sections for electron-impact excitation of the 2s; ^2S arrow 2p ; ^2P transition in B^2+ and C^3+ have been measured in the threshold region using the merged electron-ion beams energy-loss technique (MEIBEL).(M.E. Bannister et al.), Phys. Rev. A 57, 278 (1998). The data for C^3+ are compared with several sets of previous measurements and found to be in

  4. RXTE Timing and Spectroscopy of a Black Hole X-Ray Binary in Outburst

    NASA Technical Reports Server (NTRS)

    Miller, Jon M.

    2004-01-01

    This program was executed primarily to observe the black hole transient GX339-4. Observations were made simultaneously with XMM-Newton in 2004 March, and observations simultaneous with Chandra will continue to be made in the fall of 2004. As the total data set has not yet been obtained, a great deal of work remains. Preliminary examination of the data has shown extremely exciting spectral features (Fe K-alpha emission lines) and timing features (strong QPOs and flaring variability) of exactly the sort we hoped to obtain. We expect that the results of these observations will be finalized over the next year. The results will be presented in 2-3 publications in refereed journals. We have requested a no-cost extension of this grant to analyze and report our findings.

  5. Orbital Evolution and orbital phase resolved spectroscopy of the HMXB pulsar 4U 1538-52 with RXTE-PCA and BeppoSAX

    E-print Network

    U. Mukherjee; H. Raichur; B. Paul; S. Naik; N. Bhatt

    2007-02-06

    We report here results from detailed timing and spectral studies of the high mass X-ray binary pulsar 4U~1538--52 over several binary periods using observations made with the Rossi X-ray Timing Explorer (RXTE) and BeppoSAX satellites. Pulse timing analysis with the 2003 RXTE data over two binary orbits confirms an eccentric orbit of the system. Combining the orbitial parameters determined from this observation with the earlier measurements we did not find any evidence of orbital decay in this X-ray binary. We have carried out orbital phase resolved spectroscopy to measure changes in the spectral parameters with orbital phase, particularly the absorption column density and the iron line flux. The RXTE-PCA spectra in the 3--20 keV energy range were fitted with a power law and a high energy cut-off alongwith a Gaussian line at $\\sim$ 6.4 keV, whereas the BeppoSAX spectra needed only a power law and Gaussian emission line at $\\sim$ 6.4 keV in the restricted energy range of 0.3--10.0 keV. An absorption along the line of sight was included for both the RXTE and BeppoSAX data. The variation of the free spectral parameters over the binary orbit was investigated and we found that the variation of the column density of absorbing material in the line of sight with orbital phase is in reasonable agreement with a simple model of a spherically symmetric stellar wind from the companion star.

  6. Structure of the Circumnuclear Region of Seyfert 2 Galaxies Revealed by RXTE Hard X-Ray Observations of NGC 4945

    NASA Technical Reports Server (NTRS)

    Madejski, G.; Zycki, P.; Done, C.; Valinia, A.; Blanco, P.; Rothschild, R.; Turek, B.

    2000-01-01

    NGC 4945 is one of the brightest Se.yfert galaxies on the sky at 100 keV, but is completely absorbed below 10 keV, implying an optical depth of the absorber to electron scattering of a few; its absorption column is probably the largest which still allows a direct view of the nucleus at hard X-ray energies. Our observations of it with the Rossi X-ray Timing Explorer (RXTE) satellite confirm the large absorption, which for a simple phenomenological fit using an absorber with Solar abundances implies a column of 4.5(sup 0.4, sub -0.4) x 10(exp 24) /sq cm. Using a a more realistic scenario (requiring Monte Carlo modeling of the scattering), we infer the optical depth to Thomson scattering of approximately 2.4. If such a scattering medium were to subtend a large solid angle from the nucleus, it should smear out any intrinsic hard X-ray variability on time scales shorter than the light travel time through it. The rapid (with a time scale of approximately a day) hard X-ray variability of NGC 4945 we observed with the RXTE implies that the bulk of the extreme absorption in this object does not originate in a parsec-size, geometrically thick molecular torus. Limits on the amount of scattered flux require that the optically thick material on parsec scales must be rather geometrically thin, subtending a half-angle < 10 deg. This is only marginally consistent with the recent determinations of the obscuring column in hard X-rays, where only a quarter of Seyfert 2s have columns which are optically thick, and presents a problem in accounting for the Cosmic X-ray Background primarily with AGN possessing the geometry as that inferred by us. The small solid angle of the obscuring material, together with the black hole mass (of approximately 1.4 x 10(exp 6) solar mass) from megamaser measurements. allows a robust determination of the source luminosity, which in turn implies that the source radiates at approximately 10% of the Eddington limit.

  7. We live in unprecedented times. In the words of NAE President Chuck Vest: "We live in the most exciting era for science and technology in human

    E-print Network

    Zhou, Chongwu

    ever closer, biology, engineering and medicine (the convergence we witness today). I will go one step a convergence of the general social sciences and #12;2 engineering. I must say that I tend to see- and which drives today's world: the notion of "engineering empowering society." As we talk about engineering

  8. The Chandra HETGS and RXTE view of GRS 1915+105

    E-print Network

    J. C. Lee; C. S. Reynolds; R. Remillard; N. S. Schulz; E. G. Blackman; A. C. Fabian

    2002-08-08

    The Chandra AO1 HETGS observation of the micro-quasar GRS 1915+105 in the low hard state reveals (1) neutral K absorption edges from Fe, Si, Mg, and S in cold gas, and (2) highly ionized (Fe XXV and Fe XXVI) absorption attributed to a hot disk, disk wind, or corona. The neutral edges reveal anomalous Si and Fe abundances which we attribute to surrounding cold material in/near the environment of GRS 1915+105. We also point out the exciting possibility for the first astrophysical detection of XAFS attributed to material in interstellar grains. We place constraints on the ionization parameter, temperature, and hydrogen equivalent number density of the absorber near the accretion disk based on the detection of the H- and He-like Fe absorption. Observed spectral changes in the ionized lines which track the light curve point to changes in both the ionizing flux and density of the absorber, supporting the presence of a flow. Details can be found in Lee et al., 2002, ApJ., 567, 1102

  9. TeV and X-ray Monitoring of LS I +61 303 With VERITAS, Swift, and RXTE

    E-print Network

    VERITAS Collaboration; A. Smith

    2007-09-27

    Between September 2006 and February 2007, the galactic binary LS I +61 303 was monitored in the TeV band with the VERITAS array of imaging Cherenkov telescopes. These observations confirm LS I +61 303 as a variable TeV gamma-ray source, with emission peaking between orbital phase 0.6 and 0.7. During this observational period, monitoring in the X-ray regime was also carried out using both the RXTE and Swift detectors, which offered complementary coverage of the source. Outbursts in the 0.2-10 keV band were observed by both satellites at close to the same orbital phase as the TeV peak during the 2 orbital cycles covered simultaneously in both bands. While this source has been extensively studied in the X-ray band in the past, this is the first observational campaign to utilize contemporaneous X-ray and TeV data on LS I +61 303.

  10. The Discovery Outburst of the X-Ray Transient IGR J17497-2821 Observed with RXTE and ATCA

    NASA Technical Reports Server (NTRS)

    Rodriquez, Jerome; Bel, Marion Cadolle; Tomsick, John A.; Corbel, Stephane; Brocksopp, Catherine; Paizis, Ada; Shaw, Simon E.; Bodaghee, Arash

    2007-01-01

    We report the results of a series of RXTE and ATCA observations of the recently discovered X-ray transient IGR J17497-2821. Our 3-200 keV PCA+HEXTE spectral analysis shows very little variations over a period of approx.10 days around the maximum of the outburst. IGR J17497-2821 is found in a typical low-hard state (LHS) of X-ray binaries (XRBs), well represented by an absorbed Comptonized spectrum with an iron edge at about 7 keV. The high value of the absorption (approx.4 x 10(exp 22/sq cm suggests that the source is located at a large distance, either close to the Galactic center or beyond. The timing analysis shows no particular features, while the shape of the power density spectra is also typical of the LHS of XRBs, with apprrox.36% rms variability. No radio counterpart is found down to a limit of 0.21 mJy at 4.80 and 8.64 GHz. Although the position of IGR J17497-2821 in the radio to X-ray flux diagram is well below the correlation usually observed in the LHS of black holes, the comparison of its X-ray properties with those of other sources leads us to suggest that it is a black hole candidate.

  11. Materials Modification by Electronic Excitation

    NASA Astrophysics Data System (ADS)

    Itoh, Noriaki; Stoneham, Marshall

    2000-12-01

    Photography is a well-known example of changing a material by exciting it with light. This book examines a special case of a more general approach, which uses new lasers or electron beams to address some of the current needs emerging in microelectronics, photonics, and nanotechnology. It analyzes the important features of the changes induced by electronic excitation, identifies what is critical, and provides a basis from which materials modification can be developed successfully. It addresses ideas such as energy localization and charge localization, with detailed comparisons of experiment and theory. It also identifies the ways this understanding links to technological needs, such as selective removal of material, controlled changes, altering the balance between process steps, and possibilities of quantum control. This book will be of particular interest to research workers in physics, chemistry, electronic engineering and materials science.

  12. Acoustically excited heated jets. 1: Internal excitation

    NASA Technical Reports Server (NTRS)

    Lepicovsky, J.; Ahuja, K. K.; Brown, W. H.; Salikuddin, M.; Morris, P. J.

    1988-01-01

    The effects of relatively strong upstream acoustic excitation on the mixing of heated jets with the surrounding air are investigated. To determine the extent of the available information on experiments and theories dealing with acoustically excited heated jets, an extensive literature survey was carried out. The experimental program consisted of flow visualization and flowfield velocity and temperature measurements for a broad range of jet operating and flow excitation conditions. A 50.8-mm-diam nozzle was used for this purpose. Parallel to the experimental study, an existing theoretical model of excited jets was refined to include the region downstream of the jet potential core. Excellent agreement was found between theory and experiment in moderately heated jets. However, the theory has not yet been confirmed for highly heated jets. It was found that the sensitivity of heated jets to upstream acoustic excitation varies strongly with the jet operating conditions and that the threshold excitation level increases with increasing jet temperature. Furthermore, the preferential Strouhal number is found not to change significantly with a change of the jet operating conditions. Finally, the effects of the nozzle exit boundary layer thickness appear to be similar for both heated and unheated jets at low Mach numbers.

  13. Montana State University 1 Computer Science

    E-print Network

    Maxwell, Bruce D.

    Montana State University 1 Computer Science A computer science degree is highly curriculum is designed with considerable flexibility, due to the numerous types of computer science jobs. Students may then select from exciting computer science electives such as artificial intelligence

  14. ALGEBRA SEMINAR TALK Department of Computer Science

    E-print Network

    Sinnamon, Gordon J.

    ALGEBRA SEMINAR TALK WITH LILA KARI Department of Computer Science The University of Western for Theoretical Computer Science" Abstract: We are now witnessing exciting interactions between computer science absorbing notions, techniques and methodologies intrinsic to computer science and mathematics, theoretical

  15. X-Ray Outbursts of Low-mass X-Ray Binary Transients Observed in the RXTE Era

    NASA Astrophysics Data System (ADS)

    Yan, Zhen; Yu, Wenfei

    2015-06-01

    We have performed a statistical study of the properties of 110 bright X-ray outbursts in 36 low-mass X-ray binary transients (LMXBTs) seen with the All-Sky Monitor (2–12 keV) on board the Rossi X-ray Timing Explorer (RXTE) in 1996–2011. We have measured a number of outburst properties, including peak X-ray luminosity, rate of change of luminosity on a daily timescale, e-folding rise and decay timescales, outburst duration, and total radiated energy. We found that the average properties, such as peak X-ray luminosity, rise and decay timescales, outburst duration, and total radiated energy of black hole LMXBTs, are at least two times larger than those of neutron star LMXBTs, implying that the measurements of these properties may provide preliminary clues to the nature of the compact object of a newly discovered LMXBT. We also found that the outburst peak X-ray luminosity is correlated with the rate of change of X-ray luminosity in both the rise and decay phases, which is consistent with our previous studies. Positive correlations between total radiated energy and peak X-ray luminosity, and between total radiated energy and the e-folding rise or decay timescale, are also found in the outbursts. These correlations suggest that the mass stored in the disk before an outburst is the primary initial condition that sets up the outburst properties seen later. We also found that the outbursts of two transient stellar-mass ultraluminous X-ray sources in M31 also roughly follow the correlations, which indicate that the same outburst mechanism works for the brighter outbursts of these two sources in M31 that reached the Eddington luminosity.

  16. A Simultaneous RXTE and XMM-Newton Observation of the Broad-Line Radio Galaxy 3C 111

    E-print Network

    Karen T. Lewis; Michael Eracleous; Mario Gliozzi; Rita M. Sambruna; Richard F. Mushotzky

    2004-12-20

    We present the results of simultaneous XMM-Newton and RXTE observations of the Broad-Line Radio Galaxy 3C 111. We find that the Compton reflection bump is extremely weak, however, broad residuals are clearly present in the spectrum near the Fe Kalpha emission line region. When fitted with a Gaussian emission line,the feature has an equivalent width of 40-100eV and full-width at half maximum of greater than 20,000 km/s, however the exact properties of this weak line are highly dependent upon the chosen continuum model. The width of the line suggests an origin in the inner accretion disk, which is, however, inconsistent with the lack of Compton reflection. We find that much of the broad residual emission can be attributed to continuum curvature. The data are consistent with a model in which the primary powerlaw continuum is reprocessed by an accretion disk which is truncated as small radii. Alternatively, the primary source could be partially covered by a dense absorber. The latter model is less attractive than the former because of the small inclination angle of the jet of 3C 111 to the line of sight. We consider it likely that the curved continuum of the partial covering model is fortuitously similar to the continuum shape of the reprocessing model. In both models, the fit is greatly improved by the addition of an unresolved Fe K alpha emission line, which could arise either in a Compton-thin obscuring torus or dense clouds lying along the line of sight. We also find that there are unacceptable residuals at low energies in the MOS data in particular, which were modeled as a Gaussian with an energy of ~1.5 keV; we attribute these residuals to calibration uncertainties of the MOS detectors.

  17. Discovery and Monitoring of a New Black Hole Candidate XTE J1752-223 with RXTE: RMS Spectrum Evolution, BH Mass and the Source Distance

    NASA Technical Reports Server (NTRS)

    Shaposhinikov, Nikolai; Markwardt, Craig; Swank, Jean; Krimm, Hans

    2010-01-01

    We report on the discovery and monitoring observations of a new galactic black hole candidate XTE J1752-223 by Rossi X-ray Timing Explorer (RXTE). The new source appeared on the X-ray sky on October 21 2009 and was active for almost 8 months. Phenomenologically, the source exhibited the low-hard/highsoft spectral state bi-modality and the variability evolution during the state transition that matches standard behavior expected from a stellar mass black hole binary. We model the energy spectrum throughout the outburst using a generic Comptonization model assuming that part of the input soft radiation in the form of a black body spectrum gets reprocessed in the Comptonizing medium. We follow the evolution of fractional root-mean-square (RMS) variability in the RXTE/PCA energy band with the source spectral state and conclude that broad band variability is strongly correlated with the source hardness (or Comptonized fraction). We follow changes in the energy distribution of rms variability during the low-hard state and the state transition and find further evidence that variable emission is strongly concentrated in the power-law spectral component. We discuss the implication of our results to the Comptonization regimes during different spectral states. Correlations of spectral and variability properties provide measurements of the BH mass and distance to the source. The spectral-timing correlation scaling technique applied to the RXTE observations during the hardto- soft state transition indicates a mass of the BH in XTE J1752-223 between 8 and 11 solar masses and a distance to the source about 3.5 kiloparsec.

  18. Disk Dominated States of 4U 1957+11: Chandra, XMM, and RXTE Observations of Ostensibly the Most Rapidly Spinning Galactic Black Hole

    E-print Network

    Michael A. Nowak; Adrienne Juett; Jeroen Homan; Yangsen Yao; Joern Wilms; Norbert S. Schulz; Claude R. Canizares

    2008-09-17

    We present simultaneous Chandra-HETG and RXTE observations of a moderate flux `soft state' of the black hole candidate 4U1957+11. These spectra, having a minimally discernible hard X-ray excess, are an excellent test of modern disk atmosphere models that include the effects of black hole spin. The HETG data show that the soft disk spectrum is only very mildly absorbed with N_H =1-2 X 10^{21} cm^-2. These data additionally reveal 13.449 A NeIX absorption consistent with the warm/hot phase of the interstellar medium. The fitted disk model implies a highly inclined disk around a low mass black hole rapidly rotating with normalized spin a*~1. We show, however, that pure Schwarzschild black hole models describe the data extremely well, albeit with large disk atmosphere ``color-correction'' factors. Standard color-correction factors can be attained if one additionally incorporates mild Comptonization. We find that the Chandra observations do not uniquely determine spin. Similarly, XMM/RXTE observations, taken only six weeks later, are equally unconstraining. This lack of constraint is partly driven by the unknown mass and unknown distance of 4U1957+11; however, it is also driven by the limited bandpass of Chandra and XMM. We therefore present a series of 48 RXTE observations taken over the span of several years and at different brightness/hardness levels. These data prefer a spin of a*~1, even when including a mild Comptonization component; however, they also show evolution of the disk atmosphere color-correction factors. If the rapid spin models with standard atmosphere color-correction factors of h_d=1.7 are to be believed, then the RXTE observations predict that 4U1957+11 can range from a 3 M_sun black hole at 10 kpc with a*~0.83 to a 16 M_sun black hole at 22 kpc with a* ~ 1, with the latter being statistically preferred.

  19. Exciting Effects of Excited 0+ Energies

    SciTech Connect

    McCutchan, E.A.; Zamfir, N.V.; Casten, R.F. [Wright Nuclear Structure Laboratory, Yale University, New Haven, CT 06520 (United States)

    2004-09-13

    The significance of considering excited 0+ states is discussed in both an experimental and theoretical context. Experimental results on possible phase transitional nuclei are presented. New calculations on Yb and Hf nuclei in the framework of the IBA-1 model are presented and compared to previous fits in this region.

  20. Project-Based Science

    ERIC Educational Resources Information Center

    Krajcik, Joe

    2015-01-01

    Project-based science is an exciting way to teach science that aligns with the "Next Generation Science Standards" ("NGSS"). By focusing on core ideas along with practices and crosscutting concepts, classrooms become learning environments where teachers and students engage in science by designing and carrying out…

  1. RXTE All-Sky Slew Survey. Catalog of X-Ray Sources at B Greater Than 10 deg

    NASA Technical Reports Server (NTRS)

    Revnivtsev, M.; Sazonov, S.; Jahoda, K.; Gilfanov, M.

    2004-01-01

    We report results of a serendipitous hard X-ray (3-20 keV), nearly all-sky (absolute value of b greater than l0 deg.) survey based on RXTE/PCA observations performed during satellite reorientations in 1996-2002. The survey is 80% (90%) complete to a 4(sigma) limiting flux of approx. = 1.8 (2.5) x 10(exp -l1) erg/s sq cm in the 3-20 keV band. The achieved sensitivity in the 3-8 keV and 8-20 keV subbands is similar to and an order of magnitude higher than that of the previously record HEAO-1 A1 and HEAO-1 A4 all-sky surveys, respectively. A combined 7 x 10(exp 3) sq. deg area of the sky is sampled to flux levels below l0(exp -11) erg/ s sq cm (3-20 keV). In total 294 sources are detected and localized to better than 1 deg. 236 (80%) of these can be confidently associated with a known astrophysical object; another 22 likely result from the superposition of 2 or 3 closely located known sources. 35 detected sources remain unidentified, although for 12 of these we report a likely soft X-ray counterpart from the ROSAT all-sky survey bright source catalog. Of the reliably identified sources, 63 have local origin (Milky Way, LMC or SMC), 64 are clusters of galaxies and 100 are active galactic nuclei (AGN). The fact that the unidentified X-ray sources have hard spectra suggests that the majority of them are AGN, including highly obscured ones (N(sub H) greater than l0(exp 23)/sq cm). For the first time we present a log N-log S diagram for extragalactic sources above 4 x l0(exp -12) erg/ s sq cm at 8-20 keV. Key words. cosmo1ogy:observations - diffuse radiation - X-rays general

  2. RXTE Observation of Cygnus X-1: III. Implications for Compton Corona and ADAF Models. Report 3; Implications for Compton Corona and ADAF Models

    NASA Technical Reports Server (NTRS)

    Nowak, Michael A.; Wilms, Joern; Vaughan, Brian A.; Dove, James B.; Begelman, Mitchell C.

    1999-01-01

    We have recently shown that a 'sphere + disk' geometry Compton corona model provides a good description of Rossi X-ray Timing Explorer (RXTE) observations of the hard/low state of Cygnus X-1. Separately, we have analyzed the temporal data provided by RXTE. In this paper we consider the implications of this timing analysis for our best-fit 'sphere + disk' Comptonization models. We focus our attention on the observed Fourier frequency-dependent time delays between hard and soft photons. We consider whether the observed time delays are: created in the disk but are merely reprocessed by the corona; created by differences between the hard and soft photon diffusion times in coronae with extremely large radii; or are due to 'propagation' of disturbances through the corona. We find that the time delays are most likely created directly within the corona; however, it is currently uncertain which specific model is the most likely explanation. Models that posit a large coronal radius [or equivalently, a large Advection Dominated Accretion Flow (ADAF) region] do not fully address all the details of the observed spectrum. The Compton corona models that do address the full spectrum do not contain dynamical information. We show, however, that simple phenomenological propagation models for the observed time delays for these latter models imply extremely slow characteristic propagation speeds within the coronal region.

  3. Exciting flavored bound states

    NASA Astrophysics Data System (ADS)

    Rojas, E.; El-Bennich, B.; de Melo, J. P. B. C.

    2014-10-01

    We study ground and radial excitations of flavor singlet and flavored pseudoscalar mesons within the framework of the rainbow-ladder truncation using an infrared massive and finite interaction in agreement with recent results for the gluon-dressing function from lattice QCD and Dyson-Schwinger equations. Whereas the ground-state masses and decay constants of the light mesons as well as charmonia are well described, we confirm previous observations that this truncation is inadequate to provide realistic predictions for the spectrum of excited and exotic states. Moreover, we find a complex conjugate pair of eigenvalues for the excited D(s) mesons, which indicates a non-Hermiticity of the interaction kernel in the case of heavy-light systems and the present truncation. Nevertheless, limiting ourselves to the leading contributions of the Bethe-Salpeter amplitudes, we find a reasonable description of the charmed ground states and their respective decay constants.

  4. Systems Science

    ERIC Educational Resources Information Center

    Christakis, Alexander; Hammond, Debora; Jackson, Michael; Laszlo, Alexander; Mitroff, Ian; Snowden, Dave; Troncale, Len; Carr-Chellman, Alison; Spector, J. Michael; Wilson, Brent

    2013-01-01

    Scholars representing the field of systems science were asked to identify what they considered to be the most exciting and imaginative work currently being done in their field, as well as how that work might change our understanding. The scholars included Alexander Christakis, Debora Hammond, Michael Jackson, Alexander Laszlo, Ian Mitroff, Dave…

  5. Multi-photon excitation microscopy.

    PubMed

    Diaspro, Alberto; Bianchini, Paolo; Vicidomini, Giuseppe; Faretta, Mario; Ramoino, Paola; Usai, Cesare

    2006-01-01

    Multi-photon excitation (MPE) microscopy plays a growing role among microscopical techniques utilized for studying biological matter. In conjunction with confocal microscopy it can be considered the imaging workhorse of life science laboratories. Its roots can be found in a fundamental work written by Maria Goeppert Mayer more than 70 years ago. Nowadays, 2PE and MPE microscopes are expected to increase their impact in areas such biotechnology, neurobiology, embryology, tissue engineering, materials science where imaging can be coupled to the possibility of using the microscopes in an active way, too. As well, 2PE implementations in noninvasive optical bioscopy or laser-based treatments point out to the relevance in clinical applications. Here we report about some basic aspects related to the phenomenon, implications in three-dimensional imaging microscopy, practical aspects related to design and realization of MPE microscopes, and we only give a list of potential applications and variations on the theme in order to offer a starting point for advancing new applications and developments. PMID:16756664

  6. Multi-photon excitation microscopy

    PubMed Central

    Diaspro, Alberto; Bianchini, Paolo; Vicidomini, Giuseppe; Faretta, Mario; Ramoino, Paola; Usai, Cesare

    2006-01-01

    Multi-photon excitation (MPE) microscopy plays a growing role among microscopical techniques utilized for studying biological matter. In conjunction with confocal microscopy it can be considered the imaging workhorse of life science laboratories. Its roots can be found in a fundamental work written by Maria Goeppert Mayer more than 70 years ago. Nowadays, 2PE and MPE microscopes are expected to increase their impact in areas such biotechnology, neurobiology, embryology, tissue engineering, materials science where imaging can be coupled to the possibility of using the microscopes in an active way, too. As well, 2PE implementations in noninvasive optical bioscopy or laser-based treatments point out to the relevance in clinical applications. Here we report about some basic aspects related to the phenomenon, implications in three-dimensional imaging microscopy, practical aspects related to design and realization of MPE microscopes, and we only give a list of potential applications and variations on the theme in order to offer a starting point for advancing new applications and developments. PMID:16756664

  7. ASCA and RXTE observations of non-thermal X-ray emission from galactic supernova remnants: G156.2+5.7

    NASA Astrophysics Data System (ADS)

    Pannuti, T. G.; Allen, G. E.

    We are conducting a survey of Galactic shell-type supernova remnants (SNRs) known or suspected to possess non-thermal components to their X-ray emission using new and archived observations made with such X-ray satellites as ROSAT, ASCA, RXTE, Chandra and XMM-Newton. This research is intended to probe the phenomenon of cosmic-ray acceleration by Galactic SNRs and estimate the maximum energy of cosmic-ray electrons accelerated by these sources. To illustrate this work, we examine the X-ray spectrum of the northwestern rim of an SNR suspected to have a non-thermal component to its X-ray emission, G156.2+5.7 (RX J04591+5147), over the energy range ?0.7-12.0 keV using observations made by the ASCA GIS and the RXTE PCA. We compare fits made to the non-thermal component using two models, a simple power law and SRCUT. Both models give acceptable fits: the photon index derived from the fit made with the power law model ( ?=2.0 +0.2-0.5) is comparable to values obtained for the bright rims of other SNRs with hard X-ray spectra. Using the SRCUT model, we derive a value of 2.42 +0.24-0.23×10 17 Hz for the cutoff frequency ?cutoff: based on this value and assuming a mean magnetic field strength of 14 ?G, we estimate the cutoff energy Ecutoff of cosmic-ray electrons accelerated by G156.2+5.7 to be ?32 TeV. This energy value is well short of the "knee" feature of the cosmic-ray spectrum.

  8. High resolution Chandra HETG and RXTE observations of GRS 1915+105 : A hot disk atmosphere & cold gas enriched in Iron and Silicon

    E-print Network

    J. C. Lee; C. S. Reynolds; N. S. Schulz; R. Remillard; E. G. Blackman; A. C. Fabian

    2001-11-07

    The time-averaged 30 ks Chandra HETGS observation of the micro-quasar GRS 1915+105 in the low hard state reveals for the first time in this source neutral K absorption edges from Fe, Si, Mg, & S. Ionized resonance absorption from H-, and He-like Fe (XXV, XXVI), Ca XX and possibly emission from neutral Fe Kalpha and ionized Fe XXV (forbidden, or the resonance emission component of a P-Cygni profile) are also seen. We report the tentative detection of the first astrophysical signature of XAFS in the photoelectric edge of Si (and possibly Fe and Mg), attributed to material in grains. The large column densities measured from the neutral edges reveal anomalous Si and Fe abundances. Scenarios for which the anomalous abundances can be attributed to surrounding cold material associated with GRS 1915+105 and/or that the enrichment may signify either a highly unusual supernova/hypernova, or external supernova activity local to the binary are discussed. We attribute the ionized features to a hot disk, disk-wind, or corona environment. These features allow for constraints on the ionization parameter (log xi > 4.15), temperature (T > 2.4 x 10^6 K), and hydrogen equivalent number density (n > 10^{12} cm^{-3}) for this region. Variability studies with simultaneous RXTE data show that the light curve count rate tracks changes in the disk blackbody and the power-law flux. Spectral changes in the Chandra data also track the behavior of the light curve, and may point to changes in both the ionizing flux and density of the absorber. A 3.69 Hz QPO and weak first harmonic is seen in the RXTE data.

  9. Positron excitation of neon

    NASA Technical Reports Server (NTRS)

    Parcell, L. A.; Mceachran, R. P.; Stauffer, A. D.

    1990-01-01

    The differential and total cross section for the excitation of the 3s1P10 and 3p1P1 states of neon by positron impact were calculated using a distorted-wave approximation. The results agree well with experimental conclusions.

  10. Exploring Excited Hadrons

    E-print Network

    Colin Morningstar

    2008-10-24

    Progress in extracting the spectrum of excited hadron resonances is reviewed and the key issues and challenges in such computations are outlined. The importance of multi-hadron states as simulations are done with lighter pion masses is discussed, and the need for all-to-all quark propagators is emphasized.

  11. Magnetostrictive resonance excitation

    DOEpatents

    Schwarz, Ricardo B. (Los Alamos, NM); Kuokkala, Veli-Tapani (Tampere, FI)

    1992-01-01

    The resonance frequency spectrum of a magnetostrictive sample is remotely determined by exciting the magnetostrictive property with an oscillating magnetic field. The permeability of a magnetostrictive material and concomitant coupling with a detection coil varies with the strain in the material whereby resonance responses of the sample can be readily detected. A suitable sample may be a magnetostrictive material or some other material having at least one side coated with a magnetostrictive material. When the sample is a suitable shape, i.e., a cube, rectangular parallelepiped, solid sphere or spherical shell, the elastic moduli or the material can be analytically determined from the measured resonance frequency spectrum. No mechanical transducers are required and the sample excitation is obtained without contact with the sample, leading to highly reproducible results and a measurement capability over a wide temperature range, e.g. from liquid nitrogen temperature to the Curie temperature of the magnetostrictive material.

  12. Apparatus for photon excited catalysis

    NASA Technical Reports Server (NTRS)

    Saffren, M. M. (inventor)

    1977-01-01

    An apparatus is described for increasing the yield of photonically excited gas phase reactions by extracting excess energy from unstable, excited species by contacting the species with the surface of a finely divided solid.

  13. Pulse excitation of bolometer bridges

    NASA Technical Reports Server (NTRS)

    Rusk, S. J.

    1972-01-01

    Driving bolometer bridge by appropriately phased excitation pulses increases signal-to-noise ratio of bolometer sensor which operates on a chopped light beam. Method allows higher applied voltage than is possible by conventional ac or dc excitation.

  14. Harmonically excited orbital variations

    SciTech Connect

    Morgan, T.

    1985-08-06

    Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs.

  15. Temperature and excitable cells

    PubMed Central

    Fillafer, Christian; Schneider, Matthias F

    2013-01-01

    Temperature affects a host of biological processes, one of which is the conduction velocity of action potentials (AP). The velocity-temperature profile of APs has remained remarkably conserved across excitable animal and plant cells. Herein, we will not analyze this behavior in terms of temperature sensitivities of single molecules (e.g., ion channels), but rather we present a phenomenological thermodynamic interpretation. By assuming that APs are acoustic phenomena, one arrives at testable predictions about the temperature-dependence of the macroscopic material properties of the excitable cell membrane. These material properties set constraints on the excitability of a cell membrane and allow us to hypothesize about its typical relaxation timescales. The presented approach—by virtue of its thermodynamic nature—is by no means limited to temperature. It applies equally well to all thermodynamic variables (e.g., mechanical stretch, pH, ion concentrations, etc.) and to underline this argument we discuss some implications and predictions for sensory physiology. PMID:24563710

  16. Get excited: reappraising pre-performance anxiety as excitement.

    PubMed

    Brooks, Alison Wood

    2014-06-01

    Individuals often feel anxious in anticipation of tasks such as speaking in public or meeting with a boss. I find that an overwhelming majority of people believe trying to calm down is the best way to cope with pre-performance anxiety. However, across several studies involving karaoke singing, public speaking, and math performance, I investigate an alternative strategy: reappraising anxiety as excitement. Compared with those who attempt to calm down, individuals who reappraise their anxious arousal as excitement feel more excited and perform better. Individuals can reappraise anxiety as excitement using minimal strategies such as self-talk (e.g., saying "I am excited" out loud) or simple messages (e.g., "get excited"), which lead them to feel more excited, adopt an opportunity mind-set (as opposed to a threat mind-set), and improve their subsequent performance. These findings suggest the importance of arousal congruency during the emotional reappraisal process. PMID:24364682

  17. Capturing Excitement: Oceanography

    ERIC Educational Resources Information Center

    Boyer, Robert E.; Butts, David P.

    1971-01-01

    Describes four elementary school earth science activities. Each student experience is designed to help children answer questions about the ocean floor, continental drift, volcanism and mountain chains. Includes a bibliography of related articles, books, and maps. (JM)

  18. Intermediate Excited States in Rhodopsin Photochemistry

    NASA Astrophysics Data System (ADS)

    Rothberg, L. J.; Yan, M.; Jedju, T. M.; Callender, R. H.; Chao, H.; Alfano, R. R.

    1996-03-01

    Recent work by Wang et.al. footnote Q. Wang et.al., Science 266, 422 (1994) reports rapid coherent photoisomerization in rhodopsin. The bathorhodopsin photoproduct appears in 200 fs and exhibits torsional oscillations which remain synchronized with the initial photoexcitation. We report transient absorption experiments which suggest that the fraction of excited rhodopsin molecules which does not isomerize in this fashion (approximately 1/3) remains in an electronically excited state, probably the twisted state described by Birge and Hubbard,footnote R. R. Birge and L. M. Hubbard, J. Am. Chem. Soc. 102, 2195 (1980) for ~ 3 ps and then reforms rhodopsin. This picture explains the long bleaching recovery time for rhodopsin and the controversial spectral dynamics which are observed in the red.

  19. The Astrophysics Science Division Annual Report 2008

    NASA Technical Reports Server (NTRS)

    Oegerle, William; Reddy, Francis; Tyler, Pat

    2009-01-01

    The Astrophysics Science Division (ASD) at Goddard Space Flight Center (GSFC) is one of the largest and most diverse astrophysical organizations in the world, with activities spanning a broad range of topics in theory, observation, and mission and technology development. Scientific research is carried out over the entire electromagnetic spectrum from gamma rays to radio wavelengths as well as particle physics and gravitational radiation. Members of ASD also provide the scientific operations for three orbiting astrophysics missions WMAP, RXTE, and Swift, as well as the Science Support Center for the Fermi Gamma-ray Space Telescope. A number of key technologies for future missions are also under development in the Division, including X-ray mirrors, and new detectors operating at gamma-ray, X-ray, ultraviolet, infrared, and radio wavelengths. This report includes the Division's activities during 2008.

  20. HER X-1 X-RAY TURN-ON MONITORED BY RXTE M. Kuster 1 , J. Wilms 1 , R. Staubert 1 , D. E. Gruber 2 , R. E. Rothschild 2 ,

    E-print Network

    Barnstedt, Jürgen

    HER X-1 X-RAY TURN-ON MONITORED BY RXTE M. Kuster 1 , J. Wilms 1 , R. Staubert 1 , D. E. Gruber 2-resolved coverage of an X-ray turn-on in the energy range from 3 to 100 keV. The increase in ux from the o#11-eclipse dip, an anomalous dip, and an eclipse occured. The spectral modeling of the turn-on data showed

  1. Search for Gluonic Excitations

    SciTech Connect

    Paul Eugenio

    2007-10-01

    Studies of meson spectra via strong decays provide insight regarding QCD at the confinement scale. These studies have led to phenomenological models for QCD such as the constituent quark model. However, QCD allows for a much richer spectrum of meson states which include extra states such as exotics, hybrids, multi-quarks, and glueballs. First discussion of the status of exotic meson searches is given followed by a discussion of plans at Jefferson Lab to double the energy of the machine to 12 GeV, which will allow us to access photoproduction of mesons in search for gluonic excited states.

  2. Search for Gluonic Excitations

    SciTech Connect

    Eugenio, Paul [Florida State University, Department of Physics, Tallahassee, Florida 32306 (United States)

    2007-10-26

    Studies of meson spectra via strong decays provide insight regarding QCD at the confinement scale. These studies have led to phenomenological models for QCD such as the constituent quark model. However, QCD allows for a much richer spectrum of meson states which include extra states such as exotics, hybrids, multi-quarks, and glueballs. First discussion of the status of exotic meson searches is given followed by a discussion of plans at Jefferson Lab to double the energy of the machine to 12 GeV, which will allow us to access photoproduction of mesons in search for gluonic excited states.

  3. Excited States and Photons

    NSDL National Science Digital Library

    The Concord Consortium

    2011-12-13

    Investigate how atoms can be excited to give off radiation (photons) with models of electron energy diagrams. Explore the effects of energy levels in atoms through interactive computer models. Learn about the different electron orbitals of an atom, and explore three-dimensional models of the atoms. Learn about photons and why they are emitted, and gain an understanding of the link between energy levels and photons as you discover how an atom?s electron configuration affects which wavelengths of light it will admit or absorb.

  4. Hybrid excitation synchronous generators for island operation

    Microsoft Academic Search

    K. Kamiev; J. Nerg; J. Pyrho?nen; V. Zaboin

    2010-01-01

    The paper discusses Hybrid Excitation Synchronous Machines (HESMs) principles and their application possibilities. HESMs combine both features of traditional wound field synchronous machines (SMs) and permanent magnet synchronous machines (PMSMs). Such electrical machines have two different rotor excitation sources: PM excitation and wound field excitation. The wound field excitation is used to control the excitation flux in the air gap,

  5. Analysis and Interpretation of Hard X-ray Emission fromthe Bullet Cluster (1E0657-56), the Most Distant Cluster of Galaxies Observed by the RXTE

    SciTech Connect

    Petrosian, Vahe; /Stanford U., Phys. Dept. /SLAC /Stanford U., Appl. Phys. Dept.; Madejski, Greg; /SLAC; Luli, Kevin; /Stanford U., Phys. Dept.

    2006-08-16

    Evidence for non-thermal activity in clusters of galaxies is well established from radio observations of synchrotron emission by relativistic electrons. New windows in the Extreme Ultraviolet and Hard X-ray ranges have provided for more powerful tools for the investigation of this phenomenon. Detection of hard X-rays in the 20 to 100 keV range have been reported from several clusters of galaxies, notably from Coma and others. Based on these earlier observations we identified the relatively high redshift cluster 1E0657-56 (also known as RX J0658-5557) as a good candidate for hard X-ray observations. This cluster, also known as the bullet cluster, has many other interesting and unusual features, most notably that it is undergoing a merger, clearly visible in the X-ray images. Here we present results from a successful RXTE observations of this cluster. We summarize past observations and their theoretical interpretation which guided us in the selection process. We describe the new observations and present the constraints we can set on the flux and spectrum of the hard X-rays. Finally we discuss the constraints one can set on the characteristics of accelerated electrons which produce the hard X-rays and the radio radiation.

  6. Quasi-Periodic Oscillations in Short Recurring Bursts of the magnetars SGR 1806-20 and SGR 1900+14 Observed With RXTE

    E-print Network

    Huppenkothen, D; Watts, A L; Gö?ü?, E

    2014-01-01

    Quasi-periodic oscillations (QPOs) observed in the giant flares of magnetars are of particular interest due to their potential to open up a window into the neutron star interior via neutron star asteroseismology. However, only three giant flares have been observed. We therefore make use of the much larger data set of shorter, less energetic recurrent bursts. Here, we report on a search for QPOs in a large data set of bursts from the two most burst-active magnetars, SGR 1806-20 and SGR 1900+14, observed with the Rossi X-ray Timing Explorer (RXTE). We find a single detection in an averaged periodogram comprising 30 bursts from SGR 1806-20, with a frequency of 57 Hz and a width of 5 Hz, remarkably similar to a giant flare QPO observed from SGR 1900+14. This QPO fits naturally within the framework of global magneto-elastic torsional oscillations employed to explain the giant flare QPOs. Additionally, we uncover a limit on the applicability of Fourier analysis for light curves with low background count rates and s...

  7. Simultaneous Observations of PKS 2155-304 with HESS, Fermi, RXTE, and Atom: Spectral Energy Distributions and Variability in a Low State

    NASA Astrophysics Data System (ADS)

    Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Barres de Almeida, U.; Bazer-Bachi, A. R.; Becherini, Y.; Behera, B.; Bernlöhr, K.; Boisson, C.; Bochow, A.; Borrel, V.; Brion, E.; Brucker, J.; Brun, P.; Bühler, R.; Bulik, T.; Büsching, I.; Boutelier, T.; Chadwick, P. M.; Charbonnier, A.; Chaves, R. C. G.; Cheesebrough, A.; Chounet, L.-M.; Clapson, A. C.; Coignet, G.; Dalton, M.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; Dickinson, H. J.; Djannati-Ataï, A.; Domainko, W.; O'C. Drury, L.; Dubois, F.; Dubus, G.; Dyks, J.; Dyrda, M.; Egberts, K.; Emmanoulopoulos, D.; Espigat, P.; Farnier, C.; Feinstein, F.; Fiasson, A.; Förster, A.; Fontaine, G.; Füßling, M.; Gabici, S.; Gallant, Y. A.; Gérard, L.; Giebels, B.; Glicenstein, J. F.; Glück, B.; Goret, P.; Göhring, D.; Hauser, D.; Hauser, M.; Heinz, S.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hoffmann, A.; Hofmann, W.; Holleran, M.; Hoppe, S.; Horns, D.; Jacholkowska, A.; de Jager, O. C.; Jahn, C.; Jung, I.; Katarzy?ski, K.; Katz, U.; Kaufmann, S.; Kendziorra, E.; Kerschhaggl, M.; Khangulyan, D.; Khélifi, B.; Keogh, D.; Klu?niak, W.; Komin, Nu.; Kosack, K.; Lamanna, G.; Lenain, J.-P.; Lohse, T.; Marandon, V.; Martin, J. M.; Martineau-Huynh, O.; Marcowith, A.; Maurin, D.; McComb, T. J. L.; Medina, M. C.; Moderski, R.; Moulin, E.; Naumann-Godo, M.; de Naurois, M.; Nedbal, D.; Nekrassov, D.; Niemiec, J.; Nolan, S. J.; Ohm, S.; Olive, J.-F.; de Oña Wilhelmi, E.; Orford, K. J.; Ostrowski, M.; Panter, M.; Arribas, M. Paz; Pedaletti, G.; Pelletier, G.; Petrucci, P.-O.; Pita, S.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raubenheimer, B. C.; Raue, M.; Rayner, S. M.; Renaud, M.; Rieger, F.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Ruppel, J.; Sahakian, V.; Santangelo, A.; Schlickeiser, R.; Schöck, F. M.; Schröder, R.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Shalchi, A.; Sikora, M.; Skilton, J. L.; Sol, H.; Spangler, D.; Stawarz, ?.; Steenkamp, R.; Stegmann, C.; Superina, G.; Szostek, A.; Tam, P. H.; Tavernet, J.-P.; Terrier, R.; Tibolla, O.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Venter, L.; Vialle, J. P.; Vincent, P.; Vivier, M.; Völk, H. J.; Volpe, F.; Wagner, S. J.; Ward, M.; Zdziarski, A. A.; Zech, A.; H.E.S.S. Collaboration; Abdo, A. A.; Ackermann, M.; Ajello, M.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Battelino, M.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chen, A. W.; Cheung, C. C.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Colafrancesco, S.; Conrad, J.; Costamante, L.; Cutini, S.; Dermer, C. D.; de Angelis, A.; de Palma, F.; Digel, S. W.; do Couto e Silva, E.; Drell, P. S.; Dubois, R.; Dubus, G.; Dumora, D.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Fleury, P.; Focke, W. B.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giordano, F.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Horan, D.; Jóhannesson, G.; Johnson, A. S.; Johnson, R. P.; Johnson, W. N.; Kadler, M.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kerr, M.; Knödlseder, J.; Kuehn, F.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S.-H.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Madejski, G. M.; Makeev, A.; Mazziotta, M. N.; McEnery, J. E.; Meurer, C.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nolan, P. L.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Rainò, S.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Rodriguez, A. Y.; Ryde, F.; Sadrozinski, H. F.-W.; Sanchez, D.; Sander, A.; Scargle, J. D.; Schalk, T. L.; Sellerholm, A.; Sgrò, C.; Shaw, M.; Smith, D. A.; Spandre, G.; Spinelli, P.; Starck, J.-L.; Strickman, M. S.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Vilchez, N.; Villata, M.; Vitale, V.; Waite, A. P.; Wood, K. S.; Ylinen, T.; Ziegler, M.; Fermi LAT Collaboration

    2009-05-01

    We report on the first simultaneous observations that cover the optical, X-ray, and high-energy gamma-ray bands of the BL Lac object PKS 2155-304. The gamma-ray bands were observed for 11 days, between 2008 August 25 and 2008 September 6 (MJD 54704-54715), jointly with the Fermi Gamma-ray Space Telescope and the HESS atmospheric Cherenkov array, providing the first simultaneous MeV-TeV spectral energy distribution (SED) with the new generation of ?-ray telescopes. The ATOM telescope and the RXTE and Swift observatories provided optical and X-ray coverage of the low-energy component over the same time period. The object was close to the lowest archival X-ray and very high energy (VHE; >100 GeV) state, whereas the optical flux was much higher. The light curves show relatively little (~30%) variability overall when compared to past flaring episodes, but we find a clear optical/VHE correlation and evidence for a correlation of the X-rays with the high-energy spectral index. Contrary to previous observations in the flaring state, we do not find any correlation between the X-ray and VHE components. Although synchrotron self-Compton models are often invoked to explain the SEDs of BL Lac objects, the most common versions of these models are at odds with the correlated variability we find in the various bands for PKS 2155-304.

  8. RXTE Observations of the Low-Mass X-Ray Binary 4U 1608-522 in Upper-Banana State

    E-print Network

    Takahashi, Hiromitsu; Makishima, Kazuo

    2011-01-01

    To investigate the physics of mass accretion onto weakly-magnetized neutron stars, 95 archival RXTE datasets of an atoll source 4U 1608-522, acquired over 1996-2004 in so-called upper-banana state, were analyzed. The object meantime exhibited 3-30 keV luminosity in the range of <~ 10^35 - 4 x 10^37 erg s^-1, assuming a distance of 3.6 kpc. The 3-30 keV PCA spectra, produced one from each dataset, were represented successfully with a combination of a soft and a hard component, of which the presence was revealed in a model-independent manner by studying spectral variations among the observations. The soft component is expressed by so-called multi-color disk model with a temperature of ~1.8 keV, and is attributed to the emission from an optically-thick standard accretion disk. The hard component is a blackbody emission with a temperature of ~2.7 keV, thought to be emitted from the neutron-star surface. As the total luminosity increases, a continuous decrease was observed in the ratio of the blackbody luminosi...

  9. A Further Study of the Luminosity-Dependent Cyclotron Resonance Energies of the Binary X-ray Pulsar 4U0115+63 with RXTE

    E-print Network

    Motoki Nakajima; Tatehiro Mihara; Kazuo Makishima; Hisako Niko

    2006-01-21

    The present paper reports on the RXTE observations of the binary X-ray pulsar 4U0115+63, covering an outburst in 1999 March-April with 44 pointings. The 3-30 keV PCA spectra and the 15-50 keV HEXTE spectra were analyzed jointly for the cyclotron resonance features. When the 3-50 keV luminosity at an assumed distance of 7 kpc was in the range (5-13)x10^{37} erg s^{-1}, harmonic double cyclotron features were observed in absorption at ~11 and ~22 keV, as was measured previously during typical outbursts. As the luminosity decreased below \\~5x10^{37} erg s^{-1}, the second resonance disappeared, and the fundamental resonance energy gradually increased, up to $\\sim$16 keV at 0.16x10^{37} erg s^{-1}. These results reconfirm the report by Mihara et al. (2004) using Ginga, who observed a single absorption at ~16 keV in a minor (~10^{37} erg s^{-1}) outburst of this object. The luminosity-dependent cyclotron resonance energy may be understood as a result of a decrease in the accretion column height, in response to a decrease in the mass accretion rate.

  10. SIMULTANEOUS OBSERVATIONS OF PKS 2155-304 WITH HESS, FERMI, RXTE, AND ATOM: SPECTRAL ENERGY DISTRIBUTIONS AND VARIABILITY IN A LOW STATE

    SciTech Connect

    Aharonian, F.; Bernloehr, K.; Bochow, A.; Buehler, R. [Max-Planck-Institut fuer Kernphysik, P.O. Box 103980, D-69029 Heidelberg (Germany); Akhperjanian, A. G. [Yerevan Physics Institute, 2 Alikhanian Brothers Street, 375036 Yerevan (Armenia); Anton, G.; Brucker, J. [Universitaet Erlangen-Nuernberg, Physikalisches Institut, Erwin-Rommel-Str. 1, D-91058 Erlangen (Germany); Barres de Almeida, U.; Chadwick, P. M. [University of Durham, Department of Physics, South Road, Durham DH1 3LE (United Kingdom); Bazer-Bachi, A. R.; Borrel, V. [Centre d'Etude Spatiale des Rayonnements, CNRS/UPS, BP 44346, F-31028 Toulouse Cedex 4 (France); Becherini, Y. [Astroparticule et Cosmologie (APC), CNRS, Universite Paris 7 Denis Diderot, 10, rue Alice Domon et Leonie Duquet, F-75205 Paris Cedex 13 (France); Behera, B. [Landessternwarte, Universitaet Heidelberg, Koenigstuhl, D-69117 Heidelberg (Germany); Boisson, C. [LUTH, Observatoire de Paris, CNRS, Universite Paris Diderot, 5 Place Jules Janssen, 92190 Meudon (France); Brion, E.; Brun, P. [IRFU/DSM/CEA, CE Saclay, F-91191 Gif-sur-Yvette, Cedex (France); Bulik, T. [Nicolaus Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warsaw (Poland); Buesching, I. [Unit for Space Physics, Northwest University, Potchefstroom 2520 (South Africa); Boutelier, T. [Laboratoire d'Astrophysique de Grenoble, INSU/CNRS, Universite Joseph Fourier, BP 53, F-38041 Grenoble Cedex 9 (France); Charbonnier, A. [LPNHE, Universite Pierre et Marie Curie Paris 6, Universite Denis Diderot Paris 7, CNRS/IN2P3, 4 Place Jussieu, F-75252, Paris Cedex 5 (France)], E-mail: lucie.gerard@apc.univ-paris7.fr, E-mail: berrie@in2p3.fr, E-mail: sanchez@poly.in2p3.fr, E-mail: jchiang@slac.stanford.edu (and others)

    2009-05-10

    We report on the first simultaneous observations that cover the optical, X-ray, and high-energy gamma-ray bands of the BL Lac object PKS 2155-304. The gamma-ray bands were observed for 11 days, between 2008 August 25 and 2008 September 6 (MJD 54704-54715), jointly with the Fermi Gamma-ray Space Telescope and the HESS atmospheric Cherenkov array, providing the first simultaneous MeV-TeV spectral energy distribution (SED) with the new generation of {gamma}-ray telescopes. The ATOM telescope and the RXTE and Swift observatories provided optical and X-ray coverage of the low-energy component over the same time period. The object was close to the lowest archival X-ray and very high energy (VHE; >100 GeV) state, whereas the optical flux was much higher. The light curves show relatively little ({approx}30%) variability overall when compared to past flaring episodes, but we find a clear optical/VHE correlation and evidence for a correlation of the X-rays with the high-energy spectral index. Contrary to previous observations in the flaring state, we do not find any correlation between the X-ray and VHE components. Although synchrotron self-Compton models are often invoked to explain the SEDs of BL Lac objects, the most common versions of these models are at odds with the correlated variability we find in the various bands for PKS 2155-304.

  11. Neutron Scattering Studies of spin excitations in hole-doped

    E-print Network

    Wang, Wei Hua

    Neutron Scattering Studies of spin excitations in hole-doped Ba0.67K0.33Fe2As2 superconductor Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA, 4 University, West Lafayette, Indiana 47907, USA. We report inelastic neutron scattering experiments on single

  12. Negative Ion Excited States

    NASA Astrophysics Data System (ADS)

    Mead, Roy D.

    This dissertation describes high-resolution tunable laser photodetachment studies of both valence and dipole -bound excited states of negative ions. Also discussed is a merged laser-ion beam photodetachment spectrometer. The photodetachment cross section of C(,2)('-) displays many sharp resonances, due to excitation of autodetaching levels of the B('2)(SIGMA)(,u)('+) valence state lying above the onset of the (C(,2) + e) continuum. The positions of approximately 1,000 resonances were measured, allowing the spectroscopic constants of the ground X('2)(SIGMA)(,g)('+) and excited B('2)(SIGMA)(,u)('+) states to be determined, including spin-rotation constants. The previously unobserved A('2)(PI)(,u) state has been characterized by deperturbation analysis. Strong A-X transitions are predicted near 2.5 microns. The widths of C(,2)('-) resonances with v = 6 -10 and J = 1-60 have also been measured, providing autodetachment rates as a function of both rotation and vibration, ranging from 10('8) to 10('11) s('-1). The first conclusive observation of an entirely new class of states, called dipole-bound or dipole-supported states, is discussed for the case of acetaldehyde enolate (vinyl oxide) negative ion. In these novel states, the extra electron is weakly bound ((TURN)5 cm('-1)) in a very diffuse orbital ((TURN)100 (ANGSTROM)) by the dipole moment of the neutral core. Weak electric fields (< 70 V/cm) are found to rapidly detach the dipole-bound electron. These dipole-bound states resemble Rydberg states of neutrals, but differ from Rydbergs in many important respects. They should be present for all neutrals with dipole moments > 2 Debye. The merged laser-ion beam (also known as coaxial -beams) spectrometer has 0.0005 cm('-1) resolution in the visible region, simultaneously achieving very high sensitivity. It employs quadrupole beam deflectors to merge and laser and negative ion beams, and can scan spectra either by scanning the laser frequency or the Doppler shift of the ion beam. Both electrons and neutral photodetachment products are detected. Even very low energy electrons (< 20 meV) are collected and counted, and the collector may be adjusted to collect either all electrons or only low energy electrons as needed.

  13. Life Science

    NSDL National Science Digital Library

    2004-01-01

    For decades, many of the nation's life science classrooms have been anything but lively. Biology has been criticized for being content heavy, overloaded with vocabulary, and tested by rote. Six to seven hundred pages of text, presented to teenagers with limited abilities to reason, constituted what in most cases was the only required science in high schools. By contrast, the classroom of a life science teacher who is moving toward the Standards provides an exciting environment for inquiry and a core of content that is smaller but in greater depth than in the past. Topics are covered in more detail, coursework is integrated, and both teachers and students feel challenged. This free selection includes an inquiry-based, life science lesson and the Table of Contents.

  14. Science Career Magazine.

    ERIC Educational Resources Information Center

    Halsey, Linda B., Ed.; Sweeley, Charles C., Ed.

    This magazine is designed for teachers and students in junior and senior high schools. It is intended to help students become more aware about what scientists and engineers do, what's new and exciting in the fields of science and engineering, and what satisfactions might be expected from a career in one of the many different areas of science and…

  15. Expanding Science Knowledge: Enabled by Nuclear Power

    NASA Technical Reports Server (NTRS)

    Clark, Karla B.

    2011-01-01

    The availability of Radioisotope Power Sources (RPSs) power opens up new and exciting mission concepts (1) New trajectories available (2) Power for long term science and operations Astonishing science value associated with these previously non-viable missions

  16. National Computational Science Education Consortium (NCSEC)

    NSDL National Science Digital Library

    Serving as a national educational computational science clearinghouse, this website offers math and science teachers everywhere an array of online educational tools and exciting teaching modules that can be used in the classroom.

  17. Fusion excitation function revisited

    E-print Network

    Ph. Eudes; Z. Basrak; F. Sébille; V. de la Mota; G. Royer; M. Zori?

    2012-09-28

    We report on a comprehensive systematics of fusion-evaporation and/or fusion-fission cross sections for a very large variety of systems over an energy range 4-155 A.MeV. Scaled by the reaction cross sections, fusion cross sections do not show a universal behavior valid for all systems although a high degree of correlation is present when data are ordered by the system mass asymmetry.For the rather light and close to mass-symmetric systems the main characteristics of the complete and incomplete fusion excitation functions can be precisely determined. Despite an evident lack of data above 15A.MeV for all heavy systems the available data suggests that geometrical effects could explain the persistence of incomplete fusion at incident energies as high as 155A.MeV.

  18. Magnetic Excitations in LaMnPO

    NASA Astrophysics Data System (ADS)

    McNally, Daniel; Simonson, Jack; Smith, Greg; Lynn, Jeff; Zhao, Yang; Aronson, Meigan

    2013-03-01

    We performed inelastic neutron scattering experiments on LaMnPO at the BT-7 triple-axis spectrometer at NIST Center for Neutron Research. LaMnPO is an insulating pnictide compound and is antiferromagnetically ordered below TN = 375 K. Constant energy scans were performed above TN, and revealed spin-spin correlations in the paramagnetic state with characteristic wavevector Q = 1.6 Å-1, near the antiferromagnetic ordering wavevector QAFM = 1.55 Å-1. We performed constant wavevector scans above and below TN and these show there is a q-dependent and temperature-dependent energy gap in the magnetic excitations that vanishes at TN = 375 K. Constant energy scans below TN show the peak in the magnetic excitations does not change up to a measured energy transfer of 15 meV, suggesting exchange interactions are quite strong. The magnetic excitations in LaMnPO are similar to those observed in the parent compounds of the iron pnictide superconductors. Research supported by a National Security Science and Engineering Faculty Fellowship by the AFOSR

  19. Optically excited states in positronium

    NASA Technical Reports Server (NTRS)

    Howell, R. H.; Ziock, Klaus P.; Magnotta, F.; Dermer, Charles D.; Failor, R. A.; Jones, K. M.

    1990-01-01

    Optical excitation are reported of the 1 3S-2 3P transition in positronium, and a second excitation from n=2 to higher n states. The experiment used light from two pulsed dye lasers. Changes in the positronium annihilation rate during and after the laser pulse were used to deduce the excited state populations. The n=2 level was found to be saturable and excitable to a substantial fraction of n=2 positronium to higher levels. Preliminary spectroscopic measurements were performed on n=14 and n=15 positronium.

  20. Metastable Quasimolecules in Excited Gases

    E-print Network

    V. N. Malnev; R. A. Naryshkin

    2008-09-09

    Quasimolecules, which consist of two differently excited atoms in a resonantly excited gas, are considered. The energy of dissociation and typical sizes of such molecules are calculated in the first order of quantum-mechanical perturbation theory with the help of the dipole-dipole interaction operator. It is shown that there exist metastable quasimolecules, whose dipole radiative transition to the ground state (two non-excited atoms) is forbidden. The lifetime of such molecules is estimated and it is shown that quasimolecules may considerably affect the transport processes in a resonantly excited gas.

  1. Go Abroad in Animal Sciences

    E-print Network

    Escher, Christine

    Go Abroad in Animal Sciences Animal Sciences Program Contact Dr. Jim Hermes Head Advisor, Department of Animal Sciences 114 Withycombe Hall Corvallis, OR http://ans.oregonstate.edu To make Animal Sciencesoffers many exciting options for you to add an international component to your degree

  2. Attosecond Photoscopy of Plasmonic Excitations

    NASA Astrophysics Data System (ADS)

    Lupetti, Mattia; Hengster, Julia; Uphues, Thorsten; Scrinzi, Armin

    2014-09-01

    We propose an experimental arrangement to image, with attosecond resolution, transient surface plasmonic excitations. The required modifications to state-of-the-art setups used for attosecond streaking experiments from solid surfaces only involve available technology. Buildup and lifetimes of surface plasmon polaritons can be extracted and local modulations of the exciting optical pulse can be diagnosed in situ.

  3. Analysis of polyphase brushless exciter

    Microsoft Academic Search

    Xiaochuan Jia; Jih-Sheng Jason Lai; Byeong-Mun Song

    2000-01-01

    This paper presents modeling and simulation of the operation of an 11 phase brushless exciter. The analytical method is based on Kron's tensor method, which is developed for dealing efficiently with the time-varying topology of an exciter circuit during a digital computer solution. The inductances, which are variable with rotor position, are calculated by the 2-D FEM method. The detailed

  4. Science Sampler : Growth Potential

    NSDL National Science Digital Library

    Dana M. Barry

    2004-01-01

    Students will enjoy carrying out this exciting and challenging research project that combines science with computers and mathematics to investigate how polyacrylate animals change in size over time when placed in water and aqueous salt solutions. The hands-on activity motivates students and provides them with enjoyable and rewarding science project experiences. Here they have an opportunity to solve a problem and use the science inquiry skills of observing, collecting, organizing, and analyzing data.

  5. Excited waves in shear layers

    NASA Technical Reports Server (NTRS)

    Bechert, D. W.

    1982-01-01

    The generation of instability waves in free shear layers is investigated. The model assumes an infinitesimally thin shear layer shed from a semi-infinite plate which is exposed to sound excitation. The acoustical shear layer excitation by a source further away from the plate edge in the downstream direction is very weak while upstream from the plate edge the excitation is relatively efficient. A special solution is given for the source at the plate edge. The theory is then extended to two streams on both sides of the shear layer having different velocities and densities. Furthermore, the excitation of a shear layer in a channel is calculated. A reference quantity is found for the magnitude of the excited instability waves. For a comparison with measurements, numerical computations of the velocity field outside the shear layer were carried out.

  6. GEOTROPIC EXCITATION IN HELIX

    PubMed Central

    Hoagland, H.; Crozier, W. J.

    1931-01-01

    Rotation of an inclined surface on which Helix is creeping straight upward, such that the axis of the animal is turned at a right angle to its previous position, but in the same plane, leads to negatively geotropic orientation after a measurable latent period or reaction time. The duration of the latent period is a function of the slope of the surface. The magnitude of the standard deviation of the mean latent period is directly proportional to the mean latent period itself, so that the relative variability of response is constant. The dependence of reaction time upon extent of displacement from symmetrical orientation in the gravitational field is found also by tilting the supporting surface, without rotation in the animal's own plane. On slopes up to 55°, the relation between latent period and the sine of the slope is hyperbolic; above this inclination, the latent period sharply declines. This change in the curve is not affected by the attachment of moderate loads to the snail's shell (up to 1/3 of its own mass), and is probably a consequence of loss of passive stable equilibrium when rotated. When added loads do not too greatly extend the snail's anterior musculature, the latent period for the geotropic reaction is decreased, and, proportionately, its ?. These facts are discussed from the standpoint that geotropic excitation in these gasteropods is due to impressed muscle-tensions. PMID:19872624

  7. LONG-TERM MULTI-WAVELENGTH STUDIES OF GRS 1915+105. I. A HIGH-ENERGY AND MID-INFRARED FOCUS WITH RXTE/INTEGRAL AND SPITZER

    SciTech Connect

    Rahoui, F.; Chaty, S.; Rodriguez, J.; Fuchs, Y.; Mirabel, I. F. [Laboratoire AIM, CEA/DSM - CNRS - Universite Paris Diderot, Irfu/Service d'Astrophysique, Bat. 709, CEA/Saclay, F-91191 Gif-sur-Yvette (France); Pooley, G. G., E-mail: frahoui@cfa.harvard.ed [Astrophysics, Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

    2010-06-01

    To date, mid-infrared properties of Galactic black hole binaries have barely been investigated in the framework of multi-wavelength campaigns. Yet, studies in this spectral domain are crucial to get complementary information on the presence of dust and/or on the physical processes such as dust heating and thermal bremsstrahlung. Here, we report a long-term multi-wavelength study of the microquasar GRS 1915+105. On the one hand, we aimed at understanding the origins of the mid-infrared emission, and on the other hand, at searching for correlation with the high-energy and/or radio activities. We observed the source at several epochs between 2004 and 2006 with the photometer IRAC and spectrometer IRS, both mounted on the Spitzer Space Telescope. When available, we completed our set of data with quasi-simultaneous RXTE/INTEGRAL high-energy and/or Ryle radio observations from public archives. We then studied the mid-infrared environment and activities of GRS 1915+105 through spectral analysis and broadband fitting of its radio to X-ray spectral energy distributions. We detected polycyclic aromatic hydrocarbon molecules in all but one IRS spectra of GRS 1915+105 which unambiguously proves the presence of a dust component, likely photoionized by the high-energy emission. We also argue that this dust is distributed in a disk-like structure heated by the companion star, as observed in some Herbig Ae/Be and isolated cool giant stars. Moreover, we show that some of the soft X-ray emission emanating from the inner regions of the accretion disk is reprocessed and thermalized in the outer part. This leads to a mid-infrared excess that is very likely correlated to the soft X-ray emission. We exclude thermal bremsstrahlung as contributing significantly in this spectral domain.

  8. Langevin analysis of fission excitation functions induced by protons

    NASA Astrophysics Data System (ADS)

    Tian, Jian; Wang, Ning; Ye, Wei

    2015-03-01

    The stochastic Langevin approach to fission is applied to analyze fission excitation functions measured in p+206Pb and p+209Bi systems. A presaddle friction strength of (3–5) × 1021 s?1 is extracted by comparing theoretical predictions with experimental data. Furthermore, the small distortion of the formed compound nuclei with respect to the spherical shape under the condition of low angular momentum suggests that experimentally, populating an excited compound system via light-ion induced reactions favors a more accurate determination of presaddle friction with a fission cross section. Supported by National Nature Science Foundation of China (11075034)

  9. The exponential increase of biomedical information can be overwhelming for researchers and patients alike. However, to Dr. Suresh K. Bhavnani this explosion presents an exciting opportunity to use his interdisciplinary background in computer science, huma

    E-print Network

    Bhavnani, Suresh K.

    to the design of decision-support systems. His journey of attempting to unlock biomedical mysteries has resultedThe exponential increase of biomedical information can be overwhelming for researchers and patients interdisciplinary background in computer science, human-computer interaction, and graphic design to unlock mysteries

  10. Industrial applications of photonuclear resonance excitation

    E-print Network

    Chichester, David Lee, 1971-

    2000-01-01

    Photonuclear resonance excitation refers to a variety of photonuclear interaction processes that lead to the excitation of a nucleus from some initial state to a higher energy nuclear state. Typical excited nuclear state ...

  11. Parametric Excitation of a DWSC 

    E-print Network

    Lakhotia, Chandan

    2011-08-08

    Parametric excitation of the DWSC (Deep Water Stable Craneship) is studied in this thesis. It occurs for a system without any external forcing, when one of the coefficients in the equation of motion (EOM) modeling the system varies with time...

  12. Collisional excitation of interstellar formaldehyde

    NASA Technical Reports Server (NTRS)

    Green, S.; Garrison, B. J.; Lester, W. A., Jr.; Miller, W. H.

    1978-01-01

    Previous calculations for rates of excitation of ortho-H2CO by collisions with He have been extended to higher rotational levels and kinetic temperatures to 80 K. Rates for para-H2CO have also been computed. Pressure-broadening widths for several spectral lines have been obtained from these calculations and are found to agree with recent data within the experimental uncertainty of 10%. Excitation of formaldehyde by collisions with H2 molecules is also discussed.

  13. Resonant transfer excitation: Interference effects

    SciTech Connect

    Shafroth, S.M. [North Carolina Univ., Chapel Hill, NC (United States). Dept. of Physics and Astronomy; Benhenni, M. [North Carolina Univ., Chapel Hill, NC (United States). Dept. of Physics and Astronomy]|[Toulouse-3 Univ., 31 (France). Lab. de Decharges dans les Gaz; Swenson, J.K. [Oak Ridge National Lab., TN (United States)]|[Lawrence Livermore National Lab., CA (United States); Schulz, M. [Oak Ridge National Lab., TN (United States)]|[Missouri Univ., Rolla, MO (United States). Dept. of Physics; Giese, J.P.; Schone, H. [Oak Ridge National Lab., TN (United States)]|[Kansas State Univ., Manhattan, KS (United States). Dept. of Physics; Vane, C.R.; Dittner, P.F.; Datz, S. [Oak Ridge National Lab., TN (United States)

    1991-12-31

    Interference effects in RTE (Resonant Transfer Excitation) can be studied for low Z projectiles via Auger electrons emitted from highly ionized fast moving projectile ions following collisions with low Z targets. RTE in ion-atom collisions is closely related to dielectronic recombination. In the latter case which is of practical interest to the fusion power program an electron with the proper velocity incident on a highly charged ion is resonantly captured and simultaneously interacts with an inner shell electron to excite it, thus forming a doubly excited state which may decay predominantly by X-ray emission for higher Z ions or by Auger electron decay for lower Z ions. The resonant velocity is that of the Auger electron emitted by the ion in the doubly excited state in RTE the electrons to be captured are in low Z atomic (typically He) or Molecular (typically H{sub 2}) targets and the ions are produced by accelerators in highly charged states with the appropriate resonant velocity. The resonance is much broadened by the velocity distribution of the target electrons. Thus the resonance width as a function of projectile energy is determined by folding the Compton profile of the target electrons with the dielectronic recombination cross sections. A weaker effect and more speculative is Two Electron Transfer Excitation. Here one target electron excites the projectile 1s electron to the 2p shell for example and the other target electron is captured to an excited state of the projectile. This effect becomes more important at projectile energies higher than the energy where the RTE cross section has its maximum value. The electron--electron interaction has been beautifully demonstrated by Zouros et al. Finally, there might be interference with shakeup. This paper will present angular distribution measurements of Auger lines so that the effects of interference between these various processes can be studied.

  14. Resonant transfer excitation: Interference effects

    SciTech Connect

    Shafroth, S.M. (North Carolina Univ., Chapel Hill, NC (United States). Dept. of Physics and Astronomy); Benhenni, M. (North Carolina Univ., Chapel Hill, NC (United States). Dept. of Physics and Astronomy Toulouse-3 Univ., 31 (France). Lab. de Decharges dans les Gaz); Swenson, J.K. (Oak Ridge National Lab., TN (United States) Lawrence Livermore National Lab., CA (United States)); Schulz, M. (Oak R

    1991-01-01

    Interference effects in RTE (Resonant Transfer Excitation) can be studied for low Z projectiles via Auger electrons emitted from highly ionized fast moving projectile ions following collisions with low Z targets. RTE in ion-atom collisions is closely related to dielectronic recombination. In the latter case which is of practical interest to the fusion power program an electron with the proper velocity incident on a highly charged ion is resonantly captured and simultaneously interacts with an inner shell electron to excite it, thus forming a doubly excited state which may decay predominantly by X-ray emission for higher Z ions or by Auger electron decay for lower Z ions. The resonant velocity is that of the Auger electron emitted by the ion in the doubly excited state in RTE the electrons to be captured are in low Z atomic (typically He) or Molecular (typically H{sub 2}) targets and the ions are produced by accelerators in highly charged states with the appropriate resonant velocity. The resonance is much broadened by the velocity distribution of the target electrons. Thus the resonance width as a function of projectile energy is determined by folding the Compton profile of the target electrons with the dielectronic recombination cross sections. A weaker effect and more speculative is Two Electron Transfer Excitation. Here one target electron excites the projectile 1s electron to the 2p shell for example and the other target electron is captured to an excited state of the projectile. This effect becomes more important at projectile energies higher than the energy where the RTE cross section has its maximum value. The electron--electron interaction has been beautifully demonstrated by Zouros et al. Finally, there might be interference with shakeup. This paper will present angular distribution measurements of Auger lines so that the effects of interference between these various processes can be studied.

  15. Performance seeking control excitation mode

    NASA Technical Reports Server (NTRS)

    Schkolnik, Gerard

    1995-01-01

    Flight testing of the performance seeking control (PSC) excitation mode was successfully completed at NASA Dryden on the F-15 highly integrated digital electronic control (HIDEC) aircraft. Although the excitation mode was not one of the original objectives of the PSC program, it was rapidly prototyped and implemented into the architecture of the PSC algorithm, allowing valuable and timely research data to be gathered. The primary flight test objective was to investigate the feasibility of a future measurement-based performance optimization algorithm. This future algorithm, called AdAPT, which stands for adaptive aircraft performance technology, generates and applies excitation inputs to selected control effectors. Fourier transformations are used to convert measured response and control effector data into frequency domain models which are mapped into state space models using multiterm frequency matching. Formal optimization principles are applied to produce an integrated, performance optimal effector suite. The key technical challenge of the measurement-based approach is the identification of the gradient of the performance index to the selected control effector. This concern was addressed by the excitation mode flight test. The AdAPT feasibility study utilized the PSC excitation mode to apply separate sinusoidal excitation trims to the controls - one aircraft, inlet first ramp (cowl), and one engine, throat area. Aircraft control and response data were recorded using on-board instrumentation and analyzed post-flight. Sensor noise characteristics, axial acceleration performance gradients, and repeatability were determined. Results were compared to pilot comments to assess the ride quality. Flight test results indicate that performance gradients were identified at all flight conditions, sensor noise levels were acceptable at the frequencies of interest, and excitations were generally not sensed by the pilot.

  16. Luminosity and spin-period evolution of GX 304-1 during outbursts from 2009 to 2013 observed with the MAXI/GSC, RXTE/PCA, and Fermi/GBM

    NASA Astrophysics Data System (ADS)

    Sugizaki, Mutsumi; Yamamoto, Takayuki; Mihara, Tatehiro; Nakajima, Motoki; Makishima, Kazuo

    2015-06-01

    A report is made on the luminosity and pulse period evolution of the Be binary X-ray pulsar GX 304-1 during a series of outbursts from 2009 to 2013 observed by MAXI/GSC, RXTE/PCA, and Fermi/GBM. In total, 12 outbursts repeated by ˜ 132.2 d were observed, which is consistent with the X-ray periodicity of this object observed in the 1970s. These 12 outbursts, together with those in the 1970s, were all found to recur with a well-defined period of 132.189 ± 0.02 d, which can be identified with the orbital period. The pulse period of ˜ 275 s, obtained from the RXTE/PCA and Fermi/GBM data, apparently exhibited a periodic modulation synchronized with the outburst period, suggesting the pulsar orbital motion, which is superposed on a secular spin-up trend throughout the entire active phase. The observed pulse period changes were successfully represented by a model composed of the binary orbital modulation and pulsar spin up caused by mass accretion through an accretion disk. The orbital elements obtained from the best-fit model, including the projected orbital semi-major axis ax sin i ? 500-600 light-s and an eccentricity e ? 0.5, are typical of Be binary X-ray pulsars.

  17. YES Mag: Science Projects

    NSDL National Science Digital Library

    Parents, are you looking for a way to excite your children about science? This website developed by YES Mag, Canada's science magazine for kids, may just have the answer. Users can find numerous fun science activities addressing many of the basic science principles and phenomena including Newton's third law, lightening, wind, and chromatography. Each activity includes pictures to assist in the implementation of the project as well as a convenient printable version. With over thirty-five activities, children are sure to have a fun learning experience.

  18. Earth Sciences Earth Sciences

    E-print Network

    Royal Holloway, University of London

    Earth Sciences Earth Sciences Undergraduate Studies #12;Department of Earth Sciences2 Royal;3Department of Earth Sciences Earth Sciences The Department of Earth Sciences at Royal Holloway.ac.uk/studyhere Contents Why study Earth Sciences? 4 Earth Sciences at Royal Holloway 5 Admissions and entry requirements 6

  19. Adjustable, Broadband, Selective Excitation with Uniform Phase

    Microsoft Academic Search

    Kristin E. Cano; Mari A. Smith; A. J. Shaka

    2002-01-01

    An advance in the problem of achieving broadband, selective, and uniform-phase excitation in NMR spectroscopy of liquids is outlined. Broadband means that, neglecting relaxation, any frequency bandwidth may be excited even when the available radiofrequency (RF) field strength is strictly limited. Selective means that sharp transition edges can be created between pure-phase excitation and no excitation at all. Uniform phase

  20. Discovery Channel: Science Fair Central

    NSDL National Science Digital Library

    The Discovery Channel promotes student participation in science fairs at this appealing, vibrant website. Users can find a terrific, thorough guide to creating science fair projects, including project ideas and lists of books and external web sites for students to utilize during their research. Students can find tip sheets for projects in many science subjects including astronomy, chemistry, and earth science. Educators can discover how to organize a science fair and parents can learn how to get involved with their children's projects. This site is a great way to excite children about science and scientific investigations.

  1. Modeling excitable systems: Reentrant tachycardia

    NASA Astrophysics Data System (ADS)

    Lancaster, Jarrett L.; Hellen, Edward H.; Leise, Esther M.

    2010-01-01

    Excitable membranes are an important type of nonlinear dynamical system, and their study can be used to provide a connection between physical and biological circuits. We discuss two models of excitable membranes important in cardiac and neural tissues. One model is based on the Fitzhugh-Nagumo equations, and the other is based on a three-transistor excitable circuit. We construct a circuit that simulates reentrant tachycardia and its treatment by surgical ablation. This project is appropriate for advanced undergraduates as a laboratory capstone project or as a senior thesis or honors project and can also be a collaborative project, with one student responsible for the computational predictions and another for the circuit construction and measurements.

  2. Outsourcing of Grid Computing Master of Science, Systems Science

    E-print Network

    Allen, Gabrielle

    Outsourcing of Grid Computing Master of Science, Systems Science Project Report submitted an overview of the outsourcing phenomenon applied to Grid Computing. Grid Computing is an exciting technology to be a void in the literature regarding the outsourcing of Grid Computing. The dearth of coverage on the topic

  3. Autoresonant excitation of antiproton plasmas.

    PubMed

    Andresen, G B; Ashkezari, M D; Baquero-Ruiz, M; Bertsche, W; Bowe, P D; Butler, E; Carpenter, P T; Cesar, C L; Chapman, S; Charlton, M; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Hangst, J S; Hardy, W N; Hayden, M E; Humphries, A J; Hurt, J L; Hydomako, R; Jonsell, S; Madsen, N; Menary, S; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; Silveira, D M; So, C; Storey, J W; Thompson, R I; van der Werf, D P; Wurtele, J S; Yamazaki, Y

    2011-01-14

    We demonstrate controllable excitation of the center-of-mass longitudinal motion of a thermal antiproton plasma using a swept-frequency autoresonant drive. When the plasma is cold, dense, and highly collective in nature, we observe that the entire system behaves as a single-particle nonlinear oscillator, as predicted by a recent theory. In contrast, only a fraction of the antiprotons in a warm plasma can be similarly excited. Antihydrogen was produced and trapped by using this technique to drive antiprotons into a positron plasma, thereby initiating atomic recombination. PMID:21405235

  4. Dynamics of Elastic Excitable Media

    E-print Network

    Julyan H. E. Cartwright; Victor M. Eguiluz; Emilio Hernandez-Garcia; Oreste Piro

    1999-05-20

    The Burridge-Knopoff model of earthquake faults with viscous friction is equivalent to a van der Pol-FitzHugh-Nagumo model for excitable media with elastic coupling. The lubricated creep-slip friction law we use in the Burridge-Knopoff model describes the frictional sliding dynamics of a range of real materials. Low-dimensional structures including synchronized oscillations and propagating fronts are dominant, in agreement with the results of laboratory friction experiments. Here we explore the dynamics of fronts in elastic excitable media.

  5. The exciting thing about recombinant DNA, Victor McElhenySite: DNA Interactive (www.dnai.org)

    NSDL National Science Digital Library

    2008-03-26

    ` Victor McElheny DNAi Location:Manipulation>Revolution>players>The controversy A new world of exploration Former science journalist Victor McElheny muses on the excitement that surrounded the new genetic technology.

  6. Safer Science: Building Safety Into Construction or Renovations

    NSDL National Science Digital Library

    Ken Roy

    2010-12-01

    Designing a new science laboratory or renovating an existing one can be an exciting experience. Though science teachers may have a better understanding of laboratory needs than most administrators, many schools tend to limit or exclude them from the plann

  7. Using observing systems to enhance ocean science education

    Microsoft Academic Search

    L. Murray; D. Gibson; J. McDonnell; M. DeLuca; L. Hotaling; M. Newman; C. Parsons

    2005-01-01

    Coastal ocean observing systems can provide exciting, real-time data and information and link ocean science to classroom instruction. The Center for Ocean Science Education Excellence Mid-Atlantic (COSEE MA) has developed a course \\

  8. Math PUrview -- News From the Actuarial Science Program

    E-print Network

    1994-1995 has been an exciting year in the Actuarial Science Program! ... if you know of high school or beginning college students interested in actuarial ... If you have worldwide web connections, check the Actuarial Science home page at.

  9. Science Shorts: More Than One Way to Investigate

    NSDL National Science Digital Library

    2007-12-01

    An exciting element of science fairs is that they give students the opportunity to explore various interests through scientific investigation. Many students, however, mistakenly think that all investigations are experiments. This lesson can help broaden students' conceptions of science.

  10. Cardiac excitation–contraction coupling

    Microsoft Academic Search

    Donald M. Bers

    2002-01-01

    Of the ions involved in the intricate workings of the heart, calcium is considered perhaps the most important. It is crucial to the very process that enables the chambers of the heart to contract and relax, a process called excitation–contraction coupling. It is important to understand in quantitative detail exactly how calcium is moved around the various organelles of the

  11. Pseudorandom selective excitation in NMR

    NASA Astrophysics Data System (ADS)

    Walls, Jamie D.; Coomes, Alexandra

    2011-09-01

    In this work, average Hamiltonian theory is used to study selective excitation under a series of small flip-angle ?-pulses ? ? {?}/{3} applied either periodically [corresponding to the DANTE pulse sequence] or aperiodically to a spin-1/2 system. First, an average Hamiltonian description of the DANTE pulse sequence is developed that is valid for frequencies either at or very far from integer multiples of {1}/{?}, where ? is the interpulse delay. For aperiodic excitation, a single resonance, ?sel, can be selectively excited if the ?-pulse phases are modulated in concert with the interpulse delays. The conditions where average Hamiltonian theory can be accurately applied to describe the dynamics under aperiodic selective pulses, which are referred to as pseudorandom-DANTE or p-DANTE sequences, are similar to those found for the DANTE sequence. Signal averaging over different p-DANTE sequences improves the apparent selectivity at ?sel by reducing the excitations at other frequencies. Experimental demonstrations of p-DANTE sequences and comparisons with the theory are presented.

  12. Pseudorandom Selective Excitation in NMR

    E-print Network

    Jamie D. Walls; Alexandra Coomes

    2010-07-20

    In this work, average Hamiltonian theory is used to study selective excitation in a spin-1/2 system evolving under a series of small flip-angle $\\theta-$pulses $(\\theta\\ll 1)$ that are applied either periodically [which corresponds to the DANTE pulse sequence] or aperiodically. First, an average Hamiltonian description of the DANTE pulse sequence is developed; such a description is determined to be valid either at or very far from the DANTE resonance frequencies, which are simply integer multiples of the inverse of the interpulse delay. For aperiodic excitation schemes where the interpulse delays are chosen pseudorandomly, a single resonance can be selectively excited if the $\\theta$-pulses' phases are modulated in concert with the time delays. Such a selective pulse is termed a pseudorandom-DANTE or p-DANTE sequence, and the conditions in which an average Hamiltonian description of p-DANTE is found to be similar to that found for the DANTE sequence. It is also shown that averaging over different p-DANTE sequences that are selective for the same resonance can help reduce excitations at frequencies away from the resonance frequency, thereby improving the apparent selectivity of the p-DANTE sequences. Finally, experimental demonstrations of p-DANTE sequences and comparisons with theory are presented.

  13. Perceptual Load Alters Visual Excitability

    ERIC Educational Resources Information Center

    Carmel, David; Thorne, Jeremy D.; Rees, Geraint; Lavie, Nilli

    2011-01-01

    Increasing perceptual load reduces the processing of visual stimuli outside the focus of attention, but the mechanism underlying these effects remains unclear. Here we tested an account attributing the effects of perceptual load to modulations of visual cortex excitability. In contrast to stimulus competition accounts, which propose that load…

  14. Building Knowledge and Intrigue: Creating an Interactive Science Museum

    NSDL National Science Digital Library

    Jeff Marshall

    2006-10-01

    The energy and enthusiasm shown by young students walking through the doors of an interactive science museum is difficult to surpass. The excitement and wonder that informal science education generates were instrumental in the author's decision to create an interactive science museum project. This project provided eighth-grade middle school students with an opportunity to review and synthesize information; collaborate with peers; become specialists in a topic; and engage, encourage, and excite younger students about science.

  15. Science in Orbit

    NASA Technical Reports Server (NTRS)

    Weber, Mary Ellen

    2005-01-01

    This talk presents the excitement of doing science in space. It reviews some of the effects of the physical adaptations that the body undergoes to the lower gravity of space. It also discusses the role of the scientist in the space environment. It also discusses the potential uses of space development, particularly with the use of the space station.

  16. Sizing Up Science Competitions

    NSDL National Science Digital Library

    Teresa F. Bettac

    1999-09-01

    Each fall, teachers receive many packets in the mail announcing exciting science contests for students. Because many of these contests promise prizes, trips, and awards for winning students and their teachers, it is tempting for teachers to try to enter e

  17. J.T. Roberts' Science Fair

    NSDL National Science Digital Library

    Ms. Greeley

    2007-11-03

    The following websites will be useful when preparing your science fair project. It is that time of year again! It is time to start planning your science fair project. All 7th and 8th grade students are required to participate in in the science fair. This is an opportunity to explore the exciting world in which we live. REQUIREMENTS: - Students will work ...

  18. Spin excitation spectra of spin–orbit coupled bosons in an optical lattice

    NASA Astrophysics Data System (ADS)

    Li, Ruo-Yan; He, Liang; Sun, Qing; Ji, An-Chun; Tian, Guang-Shan

    2015-05-01

    Spin-wave excitation plays important roles in the investigation of the magnetic phases. In this paper, we study the spin-wave excitation spectra of two-component Bose gases with spin–orbit coupling in a deep square optical lattice using the spin-wave theory. We find that, while the excitation spectrum of the vortex crystal phase is gapless with a linear dispersion in the vicinity of the minimum point, the spectra of the commensurate spiral spin phase and the skyrmion crystal phase are gapped. Significantly, the spin fluctuations strongly destabilize the classical ground state of the skyrmion phase with the appearance of an imaginary part in the eigenfrequencies of spin excitations. Such features of the spin excitation spectra provide further insights into the exotic spin phases. Project supported by the National Natural Science Foundation of China (Grant Nos. 11347197, 11404225, and 11474205).

  19. Photoionization of excited molecular states using multiphoton excitation techniques

    NASA Astrophysics Data System (ADS)

    Dehmer, P. M.; Pratt, S. T.; Dehmer, J. L.

    1984-09-01

    Photoelectron spectra are reported for three photon resonant, four photon ionization of H2 via the B 1?+u, v=7 (J=2,4) and C 1?u, v=0-4 (J=1) levels and of N2 via the o3 1?u, v=1,2, b 1?u, v=3-5, and c 1?u, v=0 levels. The results reflect both the spectroscopy and the dynamics of photoionization of excited molecular states and are discussed in terms of the selection rules for photoionization and the relative probabilities of photoionization from Rydberg and valence states. In some cases, in accordance with the Franck-Condon principle, the results demonstrate that resonant multiphoton ionization through Rydberg states may be a powerful technique for the production of electronic, vibrational, and rotational state selected ions. However, in other cases, systematic departures from Franck-Condon factors are observed, which reflect the more subtle dynamics of excited state photoionization.

  20. The Internet Encyclopedia of Science

    NSDL National Science Digital Library

    Visitors can learn astonishing facts in historical astronomy, astrobiology, astrophysics, space missions, and many more space science topics at this comprehensive website. David Darling, a British astronomer and science writer, provides straightforward explanations of seemingly difficult concepts. In addition to an easily navigable alphabetical list and a keyword search, the encyclopedia is interlinked so that users can easily progress through the materials. The website also features the latest space science news stories as well as archives of exciting events.

  1. Variability and Spectral Studies of Luminous Seyfert 1 Galaxy Fairall 9. Search for the Reflection Component is a Quasar: RXTE and ASCA Observation of a Nearby Radio-Quiet Quasar MR 2251-178

    NASA Technical Reports Server (NTRS)

    Leighly, Karen M.

    1999-01-01

    Monitoring observations with interval of 3 days using RXTE (X Ray Timing Explorer) of the luminous Seyfert 1 galaxy Fairall 9 were performed for one year. The purpose of the observations were to study the variability of Fairall 9 and compare the results with those from the radio-loud object 3C 390.3. The data has been received and analysis is underway, using the new background model. An observation of the quasar MR 2251-178 was made in order to determine whether or not it has a reflection component. Older background models gave an unacceptable subtraction and analysis is underway using the new background model. The observation of NGC 6300 showed that the X-ray spectrum from this Seyfert 2 galaxy appears to be dominated by Compton reflection.

  2. Autoresonant excitation of dark solitons

    NASA Astrophysics Data System (ADS)

    Borich, M. A.; Shagalov, A. G.; Friedland, L.

    2015-01-01

    Continuouslyphase-locked (autoresonant) dark solitons of the defocusing nonlinear Schrodinger equation are excited and controlled by driving the system by a slowly chirped wavelike perturbation. The theory of these excitations is developed using Whitham's averaged variational principle and compared with numerical simulations. The problem of the threshold for transition to autoresonance in the driven system is studied in detail, focusing on the regime when the weakly nonlinear frequency shift in the problem differs from the typical quadratic dependence on the wave amplitude. The numerical simulations in this regime show a deviation of the autoresonance threshold on the driving amplitude from the usual 3/4 power dependence on the driving frequency chirp rate. The theory of this effect is suggested.

  3. Autoresonant excitation of dark solitons.

    PubMed

    Borich, M A; Shagalov, A G; Friedland, L

    2015-01-01

    Continuouslyphase-locked (autoresonant) dark solitons of the defocusing nonlinear Schrodinger equation are excited and controlled by driving the system by a slowly chirped wavelike perturbation. The theory of these excitations is developed using Whitham's averaged variational principle and compared with numerical simulations. The problem of the threshold for transition to autoresonance in the driven system is studied in detail, focusing on the regime when the weakly nonlinear frequency shift in the problem differs from the typical quadratic dependence on the wave amplitude. The numerical simulations in this regime show a deviation of the autoresonance threshold on the driving amplitude from the usual 3/4 power dependence on the driving frequency chirp rate. The theory of this effect is suggested. PMID:25679688

  4. Spatiotemporal control of nanooptical excitations

    PubMed Central

    Aeschlimann, Martin; Bauer, Michael; Bayer, Daniela; Brixner, Tobias; Cunovic, Stefan; Dimler, Frank; Fischer, Alexander; Pfeiffer, Walter; Rohmer, Martin; Schneider, Christian; Steeb, Felix; Strüber, Christian; Voronine, Dmitri V.

    2010-01-01

    The most general investigation and exploitation of light-induced processes require simultaneous control over spatial and temporal properties of the electromagnetic field on a femtosecond time and nanometer length scale. Based on the combination of polarization pulse shaping and time-resolved two-photon photoemission electron microscopy, we demonstrate such control over nanoscale spatial and ultrafast temporal degrees of freedom of an electromagnetic excitation in the vicinity of a nanostructure. The time-resolved cross-correlation measurement of the local photoemission yield reveals the switching of the nanolocalized optical near-field distribution with a lateral resolution well below the diffraction limit and a temporal resolution on the femtosecond time scale. In addition, successful adaptive spatiotemporal control demonstrates the flexibility of the method. This flexible simultaneous control of temporal and spatial properties of nanophotonic excitations opens new possibilities to tailor and optimize the light–matter interaction in spectroscopic methods as well as in nanophotonic applications. PMID:20212153

  5. Receiver-exciter controller design

    NASA Astrophysics Data System (ADS)

    Jansma, P. A.

    1982-06-01

    A description of the general design of both the block 3 and block 4 receiver-exciter controllers for the Deep Space Network (DSN) Mark IV-A System is presented along with the design approach. The controllers are designed to enable the receiver-exciter subsystem (RCV) to be configured, calibrated, initialized and operated from a central location via high level instructions. The RECs are designed to be operated under the control of the DMC subsystem. The instructions are in the form of standard subsystem blocks (SSBs) received via the local area network (LAN). The centralized control provided by RECs and other DSCC controllers in Mark IV-A is intended to reduce DSN operations costs from the Mark III era.

  6. Receiver-exciter controller design

    NASA Technical Reports Server (NTRS)

    Jansma, P. A.

    1982-01-01

    A description of the general design of both the block 3 and block 4 receiver-exciter controllers for the Deep Space Network (DSN) Mark IV-A System is presented along with the design approach. The controllers are designed to enable the receiver-exciter subsystem (RCV) to be configured, calibrated, initialized and operated from a central location via high level instructions. The RECs are designed to be operated under the control of the DMC subsystem. The instructions are in the form of standard subsystem blocks (SSBs) received via the local area network (LAN). The centralized control provided by RECs and other DSCC controllers in Mark IV-A is intended to reduce DSN operations costs from the Mark III era.

  7. Nuclear spin and isospin excitations

    Microsoft Academic Search

    Franz Osterfeld

    1992-01-01

    A review is given of our present knowledge of collective spin-isospin excitations in nuclei. Most of this knowledge comes from intermediate-energy charge-exchange reactions and from inelastic electron- and proton-scattering experiments. The nuclear-spin dynamics is governed by the spin-isospin-dependent two-nucleon interaction in the medium. This interaction gives rise to collective spin modes such as the giant Gamow-Teller resonances. An interesting phenomenon

  8. Monopole Excitation to Cluster States

    E-print Network

    Taiichi Yamada; Yasuro Funaki; Hisashi Horiuchi; Kiyomi Ikeda; Akihiro Tohsaki

    2008-08-30

    We discuss strength of monopole excitation of the ground state to cluster states in light nuclei. We clarify that the monopole excitation to cluster states is in general strong as to be comparable with the single particle strength and shares an appreciable portion of the sum rule value in spite of large difference of the structure between the cluster state and the shell-model-like ground state. We argue that the essential reasons of the large strength are twofold. One is the fact that the clustering degree of freedom is possessed even by simple shell model wave functions. The detailed feature of this fact is described by the so-called Bayman-Bohr theorem which tells us that SU(3) shell model wave function is equivalent to cluster model wave function. The other is the ground state correlation induced by the activation of the cluster degrees of freedom described by the Bayman-Bohr theorem. We demonstrate, by deriving analytical expressions of monopole matrix elements, that the order of magnitude of the monopole strength is governed by the first reason, while the second reason plays a sufficient role in reproducing the data up to the factor of magnitude of the monopole strength. Our explanation is made by analysing three examples which are the monopole excitations to the $0^+_2$ and $0^+_3$ states in $^{16}$O and the one to the $0^+_2$ state in $^{12}$C. The present results imply that the measurement of strong monopole transitions or excitations is in general very useful for the study of cluster states.

  9. Transverse excitation type laser oscillator

    SciTech Connect

    Akiba, T.; Hishii, M.; Nagai, H.; Shibayama, K.

    1982-08-03

    A high pressure transverse excitation type laser oscillator comprises a plane anode and a plurality of rod type cathodes to form glow discharge. Each cathode is covered with a cylindrical insulator having heat resistance except for a small discharge surface whereby the shift of the glow discharge caused by varying the pressure or the discharge current can be prevented to thus obtain stable glow discharge.

  10. Sloshing motions in excited tanks

    Microsoft Academic Search

    Jannette B. Frandsen

    2004-01-01

    A fully non-linear finite difference model has been developed based on inviscid flow equations. Numerical experiments of sloshing wave motion are undertaken in a 2-D tank which is moved both horizontally and vertically. Results of liquid sloshing induced by harmonic base excitations are presented for small to steep non-breaking waves. The simulations are limited to a single water depth above

  11. Electronic Excitations in Bilayer Graphene

    Microsoft Academic Search

    J. H. Ho; Y. H. Lai; M. F. Lin

    2007-01-01

    The pi-electronic excitations are studied for the AA- and AB-stacked bilayer graphene within the linear self-consistent-field approach. They are strongly affected by the stacking sequence, the interlayer atomic interactions, the interlayer Coulomb interactions, and the magnitude of the transferred momentum. However, they hardly depend on the direction of the transferred momentum and the temperature. There are three low-frequency plasmon modes

  12. Local Optical Excitations in Metals

    NASA Astrophysics Data System (ADS)

    Gibbs, Laurence Kay Doon

    Core spectra of p('6) (--->) p('5)s excitations of rare gas, halogen, and alkali impurities located on the surface and in the bulk of host alkali and Mg metals are presented. The data were obtained by means of differential reflectance spectroscopy in the energy range 5-20 eV using synchrotron radiation. In striking contrast to the absorption profiles of the pure alkalis, linear redshifted profiles are observed at dilution for rare gas adsorbates on alkali surfaces, for Cs adsorbed on Mg, and for Cs dispersed in bulk Na as an alloy. When Cs is dispersed in bulk K the sharp edge characteristic of the pure alkalis is observed. The spectra of Cs and Rb adsorbates on alkali surfaces mirror these same trends, but retain a distinct atomic character. A central result of the present research is that the linear profile may be associated with strong coupling of the excitation to the conduction electrons. A criterion for strong coupling is given which depends on the degree to which the excited impurity level mixes with the host conduction band. There is not at present any theory which can explain these observations. Spectra of halogen adsorbates on alkali and Mg surfaces are also presented; it is found that the ground configuration of isolated halogen atoms on these surfaces is ionic. All the impurity-metal complexes are studied at high concentration when impurity-impurity interactions are important.

  13. Channelopathies of skeletal muscle excitability.

    PubMed

    Cannon, Stephen C

    2015-04-01

    Familial disorders of skeletal muscle excitability were initially described early in the last century and are now known to be caused by mutations of voltage-gated ion channels. The clinical manifestations are often striking, with an inability to relax after voluntary contraction (myotonia) or transient attacks of severe weakness (periodic paralysis). An essential feature of these disorders is fluctuation of symptoms that are strongly impacted by environmental triggers such as exercise, temperature, or serum K(+) levels. These phenomena have intrigued physiologists for decades, and in the past 25 years the molecular lesions underlying these disorders have been identified and mechanistic studies are providing insights for therapeutic strategies of disease modification. These familial disorders of muscle fiber excitability are "channelopathies" caused by mutations of a chloride channel (ClC-1), sodium channel (NaV1.4), calcium channel (CaV1.1), and several potassium channels (Kir2.1, Kir2.6, and Kir3.4). This review provides a synthesis of the mechanistic connections between functional defects of mutant ion channels, their impact on muscle excitability, how these changes cause clinical phenotypes, and approaches toward therapeutics. PMID:25880512

  14. Resource Paper: Molecular Excited State Relaxation Processes.

    ERIC Educational Resources Information Center

    Rhodes, William

    1979-01-01

    Develops the concept of oscillatory v dissipative limits as it applies to electronic excited state processes in molecular systems. Main emphasis is placed on the radiative and nonradiative dynamics of the excited state of a molecule prepared by interaction with light or some other excitation source. (BT)

  15. 46 CFR 111.12-3 - Excitation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...static exciter may be used for excitation of an emergency generator unless it is provided with a permanent magnet or a residual-magnetism-type exciter that has the capability of voltage build-up after two months of no operation....

  16. 46 CFR 111.12-3 - Excitation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...static exciter may be used for excitation of an emergency generator unless it is provided with a permanent magnet or a residual-magnetism-type exciter that has the capability of voltage build-up after two months of no operation....

  17. 46 CFR 111.12-3 - Excitation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...static exciter may be used for excitation of an emergency generator unless it is provided with a permanent magnet or a residual-magnetism-type exciter that has the capability of voltage build-up after two months of no operation....

  18. 46 CFR 111.12-3 - Excitation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...static exciter may be used for excitation of an emergency generator unless it is provided with a permanent magnet or a residual-magnetism-type exciter that has the capability of voltage build-up after two months of no operation....

  19. 46 CFR 111.12-3 - Excitation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...static exciter may be used for excitation of an emergency generator unless it is provided with a permanent magnet or a residual-magnetism-type exciter that has the capability of voltage build-up after two months of no operation....

  20. Dynamical magnetic excitations in adatoms and dimers on metallic surfaces

    NASA Astrophysics Data System (ADS)

    Lounis, Samir; Costa, Antonio T.; Muniz, Roberto B.; Mills, Doug L.

    2012-02-01

    There is hardly any method which has shaped nanoscience and nanotechnology more profoundly than the scanning tunneling microscope. Such a tool is used nowadays to probe spin-excitations in nano-objects[1,2,3,4]. A key quantity describing these excitations is the transverse dynamical magnetic susceptibility that we calculate using the Korringa-Kohn-Rostoker Green function method within the framework of time-dependent density functional theory[5]. The behavior of adatoms and dimers will be discussed and comparison to experimental works will be provided when available. [4pt] [1] C. F. Hirjibehedin et al., Science 317, 1199 (2007)[2] T. Balashov et al., Phys. Rev. Lett. 102, 257203 (2009)[3] A. A. Khajetoorians et al., Phys. Rev. Lett. 106, 037205 (2011)[4] B. Chilian et al., Arxiv:1108.2443[5] S. Lounis et al., Phys, Rev, Lett. 105, 187205 (2010); Phys. Rev. B 83, 035109 (2011)

  1. Photoionization of excited molecular states using multiphoton excitation techniques

    NASA Astrophysics Data System (ADS)

    Dehmer, P. M.; Pratt, S. T.; Dehmer, J. L.

    Resonantly enhanced multiphoton ionization (REMPI) affords the opportunity to select a specific ionization pathway in order to produce a particular ionic state for further study or to investigate detailed aspects of excited state photoionization dynamics. The production of electronic or vibrational state-selected ions using REMPI is achieved by first preparing an intermediate Rydberg state that has a potential energy curve similar to that of the final desired ionic state, and then ionizing the Rydberg state with a single additional photon. Under these circumstances, the Franck-Condon factors governing the final ionization step strongly favor the preservation of the Rydberg state core.

  2. Peculiarities of collisional excitation transfer with excited screened energy levels of atoms

    SciTech Connect

    Gerasimov, V. A. [Institute of Atmospheric Optics, Siberian Branch of the Russian Academy of Sciences, Tomsk, 634055 (Russian Federation); Gerasimov, V. V. [Institute of Atmospheric Optics, Siberian Branch of the Russian Academy of Sciences, Tomsk, 634055 (Russian Federation); Department of Physics, Tomsk State University, Tomsk, 634050 (Russian Federation); Pavlinskiy, A. V. [Institute of High Current Electronics, Siberian Branch of the Russian Academy of Sciences, Tomsk, 634055 (Russian Federation)

    2007-09-15

    We report an experimental discovery of deviations from the known regularities in collisional excitation transfer processes for metal atoms. The collisional excitation transfer with excited screened energy levels of thulium and dysprosium atoms is studied. The selecting role of the screening 6s shell in collisional excitation transfer is shown.

  3. NRC Earth Science Decadal Survey-Mission Concept Earth Sciences from the Astronomer's Perspective, a Deep

    E-print Network

    Christian, Eric

    NRC Earth Science Decadal Survey-Mission Concept Earth Sciences from the Astronomer's Perspective Irina Melnikova #12;1 Earth Sciences from the Astronomer's Perspective 1.0 Mission Concept and Purpose Earth observations from satellites located in deep space offer the exciting opportunity to look

  4. Theoretical studies of electronically excited states

    SciTech Connect

    Besley, Nicholas A. [School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD (United Kingdom)

    2014-10-06

    Time-dependent density functional theory is the most widely used quantum chemical method for studying molecules in electronically excited states. However, excited states can also be computed within Kohn-Sham density functional theory by exploiting methods that converge the self-consistent field equations to give excited state solutions. The usefulness of single reference self-consistent field based approaches for studying excited states is demonstrated by considering the calculation of several types of spectroscopy including the infrared spectroscopy of molecules in an electronically excited state, the rovibrational spectrum of the NO-Ar complex, core electron binding energies and the emission spectroscopy of BODIPY in water.

  5. Vibrationally Excited C$_4$H

    E-print Network

    Cooksy, Andrew L; Killian, T C; Thaddeus, P; Patel, Nimesh A; Young, Ken H; McCarthy, M C

    2015-01-01

    Rotational spectra in four new excited vibrational levels of the linear carbon chain radical C$_4$H radical were observed in the millimeter band between 69 and 364 GHz in a low pressure glow discharge, and two of these were observed in a supersonic molecular beam between 19 and 38 GHz. All have rotational constants within 0.4% of the $^2\\Sigma^+$ ground vibrational state of C$_4$H and were assigned to new bending vibrational levels, two each with $^2\\Sigma$ and $^2\\Pi$ vibrational symmetry. The new levels are tentatively assigned to the $1\

  6. Electron excitation coefficients in xenon

    Microsoft Academic Search

    A. Strinic; G. Malovic; J. Bozin; Z. Lj. Petrovic

    1999-01-01

    We have performed measurements of excitation coefficients for electron swarms in xenon for the range of E\\/N from 90 Td to 10 kTd. The measurements were performed for 2p_1, 2p_2, 2p_3, 2p_4, 2p_5, 2p_6, 3p_5, 3p_6, 3p_7, 3p_8, and 3p_10 levels of neutral xenon and for 6p^4D^0 and 6p^4P^0 of xenon ion. The results were obtained in self-sustained low current

  7. SCIENCE CHINA Technological Sciences

    E-print Network

    Wang, Zhong L.

    SCIENCE CHINA Technological Sciences © Science China Press and Springer-Verlag Berlin Heidelberg and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China; 2 Institute of Theoretical Physics, Lanzhou University, Lanzhou 730000, China; 3 School of Material Science and Engineering, Georgia Institute

  8. Nerve membrane excitation without threshold.

    PubMed

    Cole, K S; Guttman, R; Bezanilla, F

    1970-04-01

    Evidence is presented to show that for a squid axon membrane the potential response, V, is a smoothly continuous function of a stimulating current, I. This makes it unlikely that an all-or-none or sharp transition phenomenon is a major factor in the processes by which ions cross the normal squid axon membrane and, probably, other excitable membranes. Spatially uniform V and I were first produced in the squid axon with internal and external electrode arrangements and later by isolating a short length of axon between external pools of sucrose. Under these simplified conditions, direct experiments and calculations based on the Hodgkin-Huxley empirical conductances agree in showing that the maximum response, R, is a continuous, single-valued function of the effect of the stimulus, S. The maximum value of DeltaR/DeltaS decreased steadily as the temperatures were increased from 25 degrees to 38 degrees C. Uncontrolled fluctuations prevented direct observations of DeltaR/DeltaS below 15 degrees C where calculations showed that it rose rapidly as the temperature decreased. Since the conductances are experimental parameters and since DeltaR/DeltaS as calculated from them remained finite and continuous event at 6.3 degrees C, this is experimental evidence against an all-or-none threshold excitation. However there is an all-or-none threshold for the initiation and propagation of an impulse along an axon where V and I are functions of both time and distance. PMID:5266158

  9. Coulomb excitation of 73Ga

    E-print Network

    J. Diriken; I. Stefanescu; D. Balabanski; N. Blasi; A. Blazhev; N. Bree; J. Cederkäll; T. E. Cocolios; T. Davinson; J. Eberth; A. Ekström; D. V. Fedorov; V. N. Fedosseev; L. M. Fraile; S. Franchoo; G. Georgiev; K. Gladnishki; M. Huyse; O. V. Ivanov; V. S. Ivanov; J. Iwanicki; J. Jolie; T. Konstantinopoulos; Th. Kröll; R. Krücken; U. Köster; A. Lagoyannis; G. Lo Bianco; P. Maierbeck; B. A. Marsh; P. Napiorkowski; N. Patronis; D. Pauwels; P. Reiter; M. Seliverstov; G. Sletten; J. Van de Walle; P. Van Duppen; D. Voulot; W. B. Walters; N. Warr; F. Wenander; K. Wrzosek

    2010-11-25

    The B(E2; Ii -> If) values for transitions in 71Ga and 73Ga were deduced from a Coulomb excitation experiment at the safe energy of 2.95 MeV/nucleon using post-accelerated beams of 71,73Ga at the REX-ISOLDE on-line isotope mass separator facility. The emitted gamma rays were detected by the MINIBALL-detector array and B(E2; Ii->If) values were obtained from the yields normalized to the known strength of the 2+ -> 0+ transition in the 120Sn target. The comparison of these new results with the data of less neutron-rich gallium isotopes shows a shift of the E2 collectivity towards lower excitation energy when adding neutrons beyond N = 40. This supports conclusions from previous studies of the gallium isotopes which indicated a structural change in this isotopical chain between N = 40 and N = 42. Combined with recent measurements from collinear laser spectroscopy showing a 1/2- spin and parity for the ground state, the extracted results revealed evidence for a 1/2-; 3/2- doublet near the ground state in 73 31Ga42 differing by at most 0.8 keV in energy.

  10. Dual excitation multiphase electrostatic drive

    SciTech Connect

    Niino, Toshiki [Inst. of Physical and Chemical Research, Wako, Saitama (Japan); Higuchi, Toshiro [Univ. of Tokyo (Japan); [Kanagawa Academy of Science and Technology, Kawasaki, Kanagawa (Japan); Egawa, Saku [Hitachi Ltd., Tsuchiura, Ibaraki (Japan). Mechanical Engineering Research Lab.

    1995-12-31

    A novel electrostatic drive technology named Dual Excitation Multiphase Electrostatic Drive (DEMED) was presented. A basic DEMED consisted of two plastic films in which 3-phase parallel electrodes were embedded and was driven by a 3-phase ac excitation to the electrodes. Static characteristics of DEMED were calculated and tested and the results agreed very well. Three prototype motors of DEMED were fabricated using commercially available technique. The first prototype consisted of a single slider and stator and generated a linear motion with a slider`s motion range of about 5mm. It weighed 7g and generated a power of 1.6W and a thrust force of 4.4N. The second prototype consisted of 50 layer stack of linear motors, summing their outputs. It weighed 3.6kg and generated a propulsive force of 310N being powered with boosted commercial 3-phase electricity. The third prototype consisted of a rotor and a stator in which electrodes were arranged radially and generated rotational motion. The maximum power of 36mW was generated by the prototype weighing only 260mg for its rotor and stator. From the results of the numerical calculation, a practical design methodology for the motor was determined. An optimal design for a motor employing currently available material and fabrication techniques is provided as an example. Analyses predict that force generation over the interfacial area between the slider and stator of this motor would be 3,900N/m{sup 2}.

  11. Nuclear excited power generation system

    SciTech Connect

    Parker, R.Z.; Cox, J.D.

    1989-03-28

    A power generation system is described, comprising: a gaseous core nuclear reactor; means for passing helium through the reactor, the helium being excited and forming alpha particles by high frequency radiation from the core of the gaseous core nuclear reactor; a reaction chamber; means for coupling chlorine and hydrogen to the reaction chamber, the helium and alpha particles energizing the chlorine and hydrogen to form a high temperature, high pressure hydrogen chloride plasma; means for converting the plasma to electromechanical energy; means for coupling the helium back to the gaseous core nuclear reactor; and means for disassociating the hydrogen chloride to form molecular hydrogen and chlorine, to be coupled back to the reaction chamber in a closed loop. The patent also describes a power generation system comprising: a gaseous core nuclear reactor; means for passing hydrogen through the reactor, the hydrogen being excited by high frequency radiation from the core; means for coupling chlorine to a reaction chamber, the hydrogen energizing the chlorine in the chamber to form a high temperature, high pressure hydrogen chloride plasma; means for converting the plasma to electromechanical energy; means for disassociating the hydrogen chloride to form molecular hydrogen and chlorine, and means for coupling the hydrogen back to the gaseous core nuclear reactor in a closed loop.

  12. Laser-based excitation and diagnostics of planar fractures

    NASA Astrophysics Data System (ADS)

    Blum, T. E.; Van Wijk, K.; Snieder, R.; Willis, M. E.

    2011-12-01

    Faults are of interest not only to earth science, but also at different scales in the non-destructive testing (NDT) community. Remote sensing of faults is of interest to both communities, with the idea of inverting for the fracture properties in a non-invasive way. Alternatively, the wave field directly excited at the fracture is of interest to both communities because the waves thus radiated are equivalent to those emitted by acoustic emissions or micro-earthquakes. Much can be learned from recording of elastic waves excited at the the fracture. Based on technology developed for NDT, we use laser ultrasonics in the laboratory to excite and detect elastic waves, in order to determine the properties of fractures or faults in laboratory rock and synthetic samples. We show examples of wave propagation in a clear Poly(methyl methacrylate) cylinder. By focusing a high power infrared (IR) laser inside the cylinder we create a visible single disk-shaped fracture near the center of the sample. The laser generates a short pulse (~20 ns) of infrared light that is absorbed by the sample material at the focal point and is converted into heat. The sudden thermal expansion generates stress and forms a fracture parallel to the cylindrical axis. We excite elastic waves at the surface of the sample using the same high-power pulsed laser, but at a much lower energy setting, and with an unfocused beam. We measure the direct and scattered wave field from the fracture with a laser interferometer, and also excite the fracture directly with a fraction of the source laser energy impinging directly on the fracture. A comparison of the direct excitation and the elastic scattered wavefields, including studies of the tip diffractions from the fracture, shows strong agreement. The measured tip diffractions carry information about the stress concentration near the crack tips, which is crucial for understanding rupture processes. This novel laboratory technique allows us to measure the source radiation pattern under various conditions, and opens new possibilities for understanding earthquake dynamics and fracture dynamics, as a function of stress loads, local excitation of the fracture, and fluid content of fractures.

  13. Hedgehog Excitations and their Superconducting Cores in the Antiferromagnetic State of SO(5) Materials

    NASA Astrophysics Data System (ADS)

    Goldbart, Paul M.

    1998-03-01

    Zhang's SO(5) approach to the physics of high-temperature superconducting materials(S.-C. Zhang, Science 275), 1089 (1997). contains the possibility that the antiferromagnetic state should support novel excitations that resemble antiferromagnetic hedgehogs at large distances but are predominantly superconducting inside a core region(P. M. Goldbart, Antiferromagnetic hedgehogs with superconducting cores); cond- mat/9711088 (UIUC Preprint P-97-10-030-iii).. Neither singular nor topologically stable, in contrast with their hedgehog cousins in pure antiferromagnetism, these excitations are what hedgehogs become when antiferromagnetic order is permitted to `` escape'' toward superconductivity---a central element in Zhang's approach. We describe the structure of antiferromagnetic hedgehog excitations with superconducting cores within the context of Zhang's approach to high-temperature superconducting materials, and touch upon a number of the experimental implications that these excitations engender.

  14. Metal-enhanced fluorescence and FRET on nanohole arrays excited at angled incidence.

    PubMed

    Poirier-Richard, H-P; Couture, M; Brule, T; Masson, J-F

    2015-07-21

    The influence of experimental parameters on the performance of plasmonic sensors is of great importance in analytical sciences. The plasmon coupling conditions (angle of incidence, metal composition, laser frequency and excitation/emission properties of fluorophores) were thus investigated for surface plasmon-enhanced fluorescence on metallic nanohole arrays. Optimal fluorescence enhancements were achieved when the plasmon resonance, the excitation laser and the fluorophore's excitation wavelengths were matched. The enhancement of the acceptor emission of a rhodamine 6G(Rh6G)-Quasar670™ FRET pair was achieved on the nanohole arrays by tuning the plasmon wavelength with the maximal overlap of the donor's emission and acceptor excitation. Silver nanohole arrays achieved larger fluorescence enhancement than gold nanohole arrays at 532 nm, while gold nanohole arrays led to larger fluorescence enhancement at 635 nm. These results demonstrate the importance of tuning the plasmon coupling conditions for surface plasmon-enhanced fluorescence sensing. PMID:25670087

  15. Experimental arrangement for lifetime measurements based on beam-foil-laser excitation

    Microsoft Academic Search

    P. D. Dumont; H. P. Garnir; Y. Baudinet-Robinet; A. El Himdy

    1988-01-01

    A new experimental arrangement based on a two step excitation as resulting from foil and laser interaction for obtaining cascade-free lifetime measurements in neutral or ionized atoms is described. A test of the apparatus is realized by measuring the lifetimes of the 2p and 3p terms in H I. On leave from Département de Physique, Faculté des Sciences, université de

  16. Mission Overview. New Horizons is an exciting scientific investigation to obtain the first close look at

    E-print Network

    Stern, S. Alan

    : http://pluto.jhuapl.edu Baseline Spacecraft Design #12;New Horizons -- A mission to explore PlutoMission Overview. New Horizons is an exciting scientific investigation to obtain the first close) spectroscopy, radio science, and in situ plasma sensors. Scheduled for launch in 2006, New Horizons could fly

  17. Pulsed Interleaved Excitation Fluctuation Imaging

    PubMed Central

    Hendrix, Jelle; Schrimpf, Waldemar; Höller, Matthias; Lamb, Don C.

    2013-01-01

    Fluorescence fluctuation imaging is a powerful means to investigate dynamics, interactions, and stoichiometry of proteins inside living cells. Pulsed interleaved excitation (PIE) is the method of nanosecond alternating excitation with time-resolved detection and allows accurate, independent, and quasi-simultaneous determination of fluorescence intensities and lifetimes of different fluorophores. In this work, we combine pulsed interleaved excitation with fluctuation imaging methods (PIE-FI) such as raster image correlation spectroscopy (RICS) or number and brightness analysis (N&B). More specifically, we show that quantitative measurements of diffusion and molecular brightness of Venus fluorescent protein (FP) can be performed in solution with PIE-RICS and compare PIE-RICS with single-point PIE-FCS measurements. We discuss the advantages of cross-talk free dual-color PIE-RICS and illustrate its proficiency by quantitatively comparing two commonly used FP pairs for dual-color microscopy, eGFP/mCherry and mVenus/mCherry. For N&B analysis, we implement dead-time correction to the PIE-FI data analysis to allow accurate molecular brightness determination with PIE-NB. We then use PIE-NB to investigate the effect of eGFP tandem oligomerization on the intracellular maturation efficiency of the fluorophore. Finally, we explore the possibilities of using the available fluorescence lifetime information in PIE-FI experiments. We perform lifetime-based weighting of confocal images, allowing us to quantitatively determine molecular concentrations from 100 nM down to <30 pM with PIE-raster lifetime image correlation spectroscopy (RLICS). We use the fluorescence lifetime information to perform a robust dual-color lifetime-based FRET analysis of tandem fluorescent protein dimers. Lastly, we investigate the use of dual-color RLICS to resolve codiffusing FRET species from non-FRET species in cells. The enhanced capabilities and quantitative results provided by PIE-FI make it a powerful method that is broadly applicable to a large number of interesting biophysical studies. PMID:23972837

  18. Pulsar Science with the SKA

    E-print Network

    Kramer, Michael

    2015-01-01

    The SKA will be transformational for many areas of science, but in particular for the study of neutron stars and their usage as tools for fundamental physics in the form of radio pulsars. Since the last science case for the SKA, numerous and unexpected advances have been made broadening the science goals even further. With the design of SKA Phase 1 being finalised, it is time to confront the new knowledge in this field, with the prospects promised by this exciting new telescope. While technically challenging, we can build our expectations on recent discoveries and technical developments that have reinforced our previous science goals.

  19. Laptops--An Exciting Addition to the Social Science Classroom.

    ERIC Educational Resources Information Center

    Riegler, Edward R.

    1992-01-01

    Describes ways laptop computers are used in two high school Advanced Placement History classes. Discusses notetaking on laptops, small group assignments via modem, cooperative-learning groups, and laptops as a research tool. (SR)

  20. All that matters Exciting developments in the physical sciences

    E-print Network

    Rogers, John A.

    you under my skin I've got you under my skin October 17, 2010 Joerg Heber Leave a comment Go devices in unusual places and for unusual applications. In biomedicine for example, if you want to put a diagnostic sensor on top of a muscle. In electronics, when you want to put a large-scale solar cell

  1. Final excitation energy of fission fragments

    SciTech Connect

    Schmidt, Karl-Heinz; Jurado, Beatriz [Centre d'Etudes Nucleaires de Bordeaux Gradignan (CENBG), CNRS/IN2P3, Chemin du Solarium, B.P. 120, F-33175 Gradignan (France)

    2011-06-15

    We study how the excitation energy of the fully accelerated fission fragments is built up. It is stressed that only the intrinsic excitation energy available before scission can be exchanged between the fission fragments to achieve thermal equilibrium. This is in contradiction with most models used to calculate prompt neutron emission, where it is assumed that the total excitation energy of the final fragments is shared between the fragments by the condition of equal temperatures. We also study the intrinsic excitation-energy partition in statistical equilibrium for different level-density descriptions as a function of the total intrinsic excitation energy of the fissioning system. Excitation energies are found to be strongly enhanced in the heavy fragment, if the level density follows a constant-temperature behavior at low energies, e.g., in the composed Gilbert-Cameron description.

  2. Deconfined fractionally charged excitation in any dimensions

    SciTech Connect

    Chern, Chyh-Hong, E-mail: chchern@ntu.edu.tw; Huang, Po-Hao; Lee, Hong-Hsi

    2013-05-15

    An exact incompressible quantum liquid is constructed at the filling factor 1/m{sup 2} in the square lattice. It supports deconfined fractionally charged excitation. At the filling factor 1/m{sup 2}, the excitation has fractional charge e/m{sup 2}, where e is the electric charge. This model can be easily generalized to the n-dimensional square lattice (integer lattice), where the charge of excitations becomes e/m{sup n}. -- Highlights: ? We demonstrate that the fractionally-charged excitations can in principle exist in any dimensions. ? We compute the fractional charge of the excitations (e{sup ?}=e/m{sup D}). ? We demonstrate that the fractionally-charged excitation is in a deconfined phase.

  3. Excitation of vascular muscle by norepinephrine

    Microsoft Academic Search

    Kent Hermsmeyer

    1983-01-01

    The mechanism by which norepinephrine causes excitation of vascular muscle is a concept that has undergone considerable change\\u000a in the last several years. Although the excitation step is absolutely fundamental to understanding constriction and dilation\\u000a of arteries, several aspects of the hypothesis are not well understood and have recently been controversial. The earliest\\u000a view of the excitation process was that

  4. Information Processing with Structured Chemical Excitable Medium

    Microsoft Academic Search

    J. Gorecki; J. N. Gorecka; Y. Igarashi; K. Yoshikawa

    2009-01-01

    \\u000a It is well known that an excitable medium can be used for information processing with pulses of excitation. In such medium\\u000a messages can be coded or in the number of pulses or in the sequences of times separating subsequent excitations. Information\\u000a is processed as the result of two major effects: interactions between pulses and interactions between a pulse and the

  5. Information processing with structured excitable medium

    Microsoft Academic Search

    Jerzy Gorecki; Joanna Natalia Gorecka; Yasuhiro Igarashi

    2009-01-01

    There are many ways in which a nonlinear chemical medium can be used for information processing. Here we are concerned with\\u000a an excitable medium and the straightforward method of information coding: a single excitation pulse represents a bit of information\\u000a and a group of excitations forms a message. Our attention is focused on a specific type of nonhomogeneous medium that

  6. Design evaluation: S-band exciters

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A design evaluation study was conducted to produce S-band exciter (SBE) system to provide a highly stable phase or modulated carrier for transmission to spacecraft. The exciter is part of an S-band receiver/exciter/ranging system at Spaceflight Tracking and Data Network (STDN) ground stations. The major features of the system are defined. Circuit diagrams of the electronic components are provided.

  7. Excited Baryons in Holographic QCD

    SciTech Connect

    de Teramond, Guy F.; /Costa Rica U.; Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins

    2011-11-08

    The light-front holographic QCD approach is used to describe baryon spectroscopy and the systematics of nucleon transition form factors. Baryon spectroscopy and the excitation dynamics of nucleon resonances encoded in the nucleon transition form factors can provide fundamental insight into the strong-coupling dynamics of QCD. The transition from the hard-scattering perturbative domain to the non-perturbative region is sensitive to the detailed dynamics of confined quarks and gluons. Computations of such phenomena from first principles in QCD are clearly very challenging. The most successful theoretical approach thus far has been to quantize QCD on discrete lattices in Euclidean space-time; however, dynamical observables in Minkowski space-time, such as the time-like hadronic form factors are not amenable to Euclidean numerical lattice computations.

  8. Multipolar excitation in triangular nanoprisms.

    PubMed

    Shuford, Kevin L; Ratner, Mark A; Schatz, George C

    2005-09-15

    Theoretical studies on the optical properties of gold triangular prisms in solution are presented to determine how structural modifications affect the extinction spectrum. Well-defined trends in the particle extinction are found to depend on the triangular edge length and the prism thickness. Calculations performed on large, thin triangular prisms indicate multipolar excitation and display numerous peaks in the extinction spectrum. The dominant peaks are assigned to different in-plane modes corresponding to the lowest three orders of a multipole expansion. Vector polarization plots are presented to support the peak assignments. Altering the prisms by snipping off the points of the triangular cross section significantly blueshifts the dipole peak, but the higher-order modes are only slightly affected. Snipping off large volumes can lead to the suppression of high-order multipoles in the extinction spectrum. PMID:16392589

  9. Collective excitations of supersymmetric plasma

    NASA Astrophysics Data System (ADS)

    Czajka, Alina; Mrówczy?ski, Stanis?aw

    2011-02-01

    Collective excitations of N=1 supersymmetric electromagnetic plasma are studied. Since the Keldysh-Schwinger approach is used, not only equilibrium but also nonequilibrium plasma, which is assumed to be ultrarelativistic, is under consideration. The dispersion equations of photon, photino, electron, and selectron modes are written down and the self-energies, which enter the equations, are computed in the hard loop approximation. The self-energies are discussed in the context of effective action which is also given. The photon modes and electron ones appear to be the same as in the usual ultrarelativistic plasma of electrons, positrons, and photons. The photino modes coincide with the electron ones and the selectron modes are as of a free relativistic massive particle.

  10. Propagating plasmon excitation of molecular junctions for spectroscopy

    NASA Astrophysics Data System (ADS)

    Evans, Charlotte; Zolotavin, Pavlo; Li, Yajing; Natelson, Doug

    2015-03-01

    Simultaneous measurements of inelastic electron tunneling spectra and surface-enhanced Raman spectroscopy (SERS) can provide critical information about how heat dissipates through a material at the molecular level by determining the electronic and vibrational energy distributions at the molecular scale. Gold bowtie nanostructures were fabricated to be used as SERS substrates, conventionally with exciting light incident directly on the molecular junction. Electromigrating these devices created interelectrode nanogaps with single-molecule sensitivity in which the Raman scattering rate is dominated by plasmonically enhanced electromagnetic fields due to the presence of the metal nanojunction near the molecules of interest. Adding metallic gratings to the electrode design enables the excitation of propagating plasmon modes that can couple into the junction region without direct excitation by far-field radiation. We will present preliminary data on how the addition of these gratings affects single-molecule SERS and the electrical properties of the molecules in these junctions. National Science Foundation Graduate Research Fellowship under Grant No. DGE-1450681 and ARO award W911 NF-13-1-0476

  11. Excitation and control of autoresonant ion acoustic waves

    NASA Astrophysics Data System (ADS)

    Friedland, Lazar

    2014-10-01

    Controlled excitation of nonlinear waves is one of the important goals of both basic and applied research. We study the excitation of large amplitude ion acoustic waves in plasmas from a trivial equilibrium by the adiabatic nonlinear phase-locking (autoresonance) with a chirped frequency drive. In this case, under certain conditions, the nonlinearity and variation of parameters work in tandem to preserve the phase-locking in the system via excursion of the ion acoustic wave in its parameter space, yielding controlled growth of the wave amplitude. We analyze formation of autoresonant ion acoustic waves via both the fluid and kinetic Vlasov-Poisson models. A weakly nonlinear, long wavelength limit of the fluid approximation for the ion acoustic waves is frequently associated with the KdV equation. We go beyond the driven KdV problem and study the formation of driven, strongly nonlinear, fluid-type ion acoustic waves. The Whitham's averaged vriational principle is applied in analyzing these autoresonant excitations. At larger ion temperatures, our simulations show the possibility of formation of a phase-locked void (hole) in the ion distribution, yielding a particular type of autoresonant ion Bernstein, Green, and Kruskal (BGK) mode. Supported by Israel Science Foundation.

  12. Spatially encoded multiple-quantum excitation

    NASA Astrophysics Data System (ADS)

    Ridge, Clark D.; Borvayeh, Leila; Walls, Jamie D.

    2013-05-01

    In this work, we present a simple method to spatially encode the transition frequencies of nuclear spin transitions and to read out these frequencies within a single scan. The experiment works by combining pulsed field gradients with an excitation sequence that selectively excites spin transitions within certain sample regions. After the initial excitation, imaging the resulting widehat{z}-magnetization is used to determine the locations where the excitations occurred, from which the corresponding transition frequencies are determined. Simple experimental demonstrations of this technique on one- and two-spin systems are presented.

  13. Spatially encoded multiple-quantum excitation.

    PubMed

    Ridge, Clark D; Borvayeh, Leila; Walls, Jamie D

    2013-05-28

    In this work, we present a simple method to spatially encode the transition frequencies of nuclear spin transitions and to read out these frequencies within a single scan. The experiment works by combining pulsed field gradients with an excitation sequence that selectively excites spin transitions within certain sample regions. After the initial excitation, imaging the resulting z?-magnetization is used to determine the locations where the excitations occurred, from which the corresponding transition frequencies are determined. Simple experimental demonstrations of this technique on one- and two-spin systems are presented. PMID:23742468

  14. Generic two-variable model of excitability

    NASA Astrophysics Data System (ADS)

    Ventura, A. C.; Mindlin, G. B.; Dawson, S. Ponce

    2002-04-01

    We present a simple model that displays all classes of two-dimensional excitable regimes. One of the variables of the model displays the usual spikes observed in excitable systems. Since the model is written in terms of a ``standard'' vector field, it is always possible to fit it to experimental data displaying spikes in an algorithmic way. In fact, we use it to fit a series of membrane potential recordings obtained in the medicinal leech and time series generated with the FitzHugh-Nagumo equations and the excitability model of Eguía et al. [Phys. Rev. E 58, 2636 (1998)]. In each case, we determine the excitability class of the corresponding system.

  15. A Science Information Infrastructure

    NASA Astrophysics Data System (ADS)

    Christian, C. A.; Hawkins, I.; Malina, R. F.; Dow, K.; Murray, S.

    1994-12-01

    We have created a partnership of science museums, research institutions, teachers, and other centers of informal science education to enable access to the rich resources of remote sensing data available from NASA and other sources and to deliver this information to the general community. We are creating science resource centers in the nation's science museums and planetarium facilities, linking them together through a national Science Information Infrastructure (SII). The SII framework is being founded on Internet connections between the resource centers, which are in turn linked to research institutions. The most up-to-date and exciting science data, related information, and interpretive material will be available from the research institutions. The science museums will present this information in appropriate ways that respond to the needs and interest of the general public and K--12 communities. The science information will be available through the World Wide Web using a Mosaic interface that individuals will use to explore the on-line materials through self-guided learning modules. K--12 teachers will have access to the materials and, in a workshop forum, learn to find and use the information to create lesson plans and curricula for their classrooms. Eventually, as the connectivity of schools and libraries improves, students and teachers will have access to the resource centers from their own locations. The core partnership of the SII includes the Center for EUV Astrophysics (CEA), and Smithsonian Astrophysical Observatory, Exploratorium, Lawrence Hall of Science, Smithsonian National Air and Space Museum, Science Museum of Virginia, New York Hall of Science, Adler Museum of Chicago, University of California Museum of Paleontology, Boston Museum of Science, and the Earth Observing Satellite Company (EOSAT). A demonstration of the application of resource center materials in the K--12 community is being conducted through the Science On-Line project at the Center for EUV Astrophysics. This work has been supported by a NASA Astrophysics Division grant and NASA contract NAS5-29298.

  16. Science Outreach Science Outreach

    E-print Network

    -wide science festival every spring. We offer interactive science activities, talks and games for the curious-school kids. Join the Scope Club and learn how to qualify for a free telescope. Science Spooktacular Share wicked science activities, phantom physics and cryptic chemistry at this annual family event. Wear your

  17. Excited state dynamics of liquid water: Insight from the dissociation reaction following two-photon excitation

    E-print Network

    Elles, Christopher G.; Shkrob, Ilya A.; Crowell, Robert A.; Bradforth, Stephen E.

    2007-04-25

    The authors use transient absorption spectroscopy to monitor the ionization and dissociation products following two-photon excitation of pure liquid water. The primary decay mechanism changes from dissociation at an excitation energy of 8.3e...

  18. Science Camp: Just for the Girls

    ERIC Educational Resources Information Center

    Cavanagh, Sean

    2007-01-01

    Research shows that girls tend to lose interest in science and math as they move through the education pipeline--a retreat that often begins during middle school. Summer science camps can be part of reversing that trend, some say. Academic camps are on the rise across the country, including ones to get adolescent girls excited about the…

  19. Reverse Your Science Fair with Educational Partnerships

    ERIC Educational Resources Information Center

    Rose, Jordan; Zardetto-Smith, Andrea; Mu, Keli; Demetrikopoulos, Melissa K.

    2004-01-01

    This article suggests several ways teachers can get their students really excited about science by bringing scientists to the science fair in a different role than the traditional "judge." With a bit more effort, scientists can become actively involved as presenters of hands-on activities. This article discusses: what happens when the tables are…

  20. Making Links between Maths and Science

    ERIC Educational Resources Information Center

    Hiscock, Naomi

    2012-01-01

    For some children maths and science are exciting subjects that work side by side, one providing the opportunity to practise and hone skills and knowledge gained from the other. For other children the subjects are disjointed and seem to bear no relationship to each other. Science can provide a wonderful opportunity to practise a variety of math…

  1. Ensemble density functional theory method correctly describes bond dissociation, excited state electron transfer, and double excitations.

    PubMed

    Filatov, Michael; Huix-Rotllant, Miquel; Burghardt, Irene

    2015-05-14

    State-averaged (SA) variants of the spin-restricted ensemble-referenced Kohn-Sham (REKS) method, SA-REKS and state-interaction (SI)-SA-REKS, implement ensemble density functional theory for variationally obtaining excitation energies of molecular systems. In this work, the currently existing version of the SA-REKS method, which included only one excited state into the ensemble averaging, is extended by adding more excited states to the averaged energy functional. A general strategy for extension of the REKS-type methods to larger ensembles of ground and excited states is outlined and implemented in extended versions of the SA-REKS and SI-SA-REKS methods. The newly developed methods are tested in the calculation of several excited states of ground-state multi-reference systems, such as dissociating hydrogen molecule, and excited states of donor-acceptor molecular systems. For hydrogen molecule, the new method correctly reproduces the distance dependence of the lowest excited state energies and describes an avoided crossing between the doubly excited and singly excited states. For bithiophene-perylenediimide stacked complex, the SI-SA-REKS method correctly describes crossing between the locally excited state and the charge transfer excited state and yields vertical excitation energies in good agreement with the ab initio wavefunction methods. PMID:25978880

  2. Ensemble density functional theory method correctly describes bond dissociation, excited state electron transfer, and double excitations

    NASA Astrophysics Data System (ADS)

    Filatov, Michael; Huix-Rotllant, Miquel; Burghardt, Irene

    2015-05-01

    State-averaged (SA) variants of the spin-restricted ensemble-referenced Kohn-Sham (REKS) method, SA-REKS and state-interaction (SI)-SA-REKS, implement ensemble density functional theory for variationally obtaining excitation energies of molecular systems. In this work, the currently existing version of the SA-REKS method, which included only one excited state into the ensemble averaging, is extended by adding more excited states to the averaged energy functional. A general strategy for extension of the REKS-type methods to larger ensembles of ground and excited states is outlined and implemented in extended versions of the SA-REKS and SI-SA-REKS methods. The newly developed methods are tested in the calculation of several excited states of ground-state multi-reference systems, such as dissociating hydrogen molecule, and excited states of donor-acceptor molecular systems. For hydrogen molecule, the new method correctly reproduces the distance dependence of the lowest excited state energies and describes an avoided crossing between the doubly excited and singly excited states. For bithiophene-perylenediimide stacked complex, the SI-SA-REKS method correctly describes crossing between the locally excited state and the charge transfer excited state and yields vertical excitation energies in good agreement with the ab initio wavefunction methods.

  3. COMPUTER SIMULATIONS OF EXCITATIONS OF A QUANTUM

    E-print Network

    Adler, Joan

    COMPUTER SIMULATIONS OF EXCITATIONS OF A QUANTUM SOLID AND OF THE MELTING TRANSITION AT HIGH PRESSURE VIACHESLAV SORKIN #12;COMPUTER SIMULATIONS OF EXCITATIONS OF A QUANTUM SOLID AND OF THE MELTING to express my gratitude to A. Weil for the help on the IUCC machines and parallel computing. I also thank

  4. Study of excited nucleons and their structure

    SciTech Connect

    Burkert, Volker D. [JLAB, Newport News, VA (United States)

    2014-01-01

    Recent advances in the study of excited nucleons are discussed. Much of the progress has been achieved due to the availability of high precision meson production data in the photoproduction and electroproduction sectors, the development of multi-channel partial wave analysis techniques, and advances in Lattice QCD with predictions of the full excitation spectrum.

  5. Imaging fingerprinting of excitation emission matrices

    Microsoft Academic Search

    Muhammad Ali Malik; Emanuela Gatto; Stephen Macken; Corrado DiNatale; Roberto Paolesse; Arnaldo D’Amico; Ingemar Lundström; Daniel Filippini

    2009-01-01

    The spectral fingerprinting of the excitation emission matrix (EEM) of fluorescent substances is demonstrated using polychromatic light sources and tri-chromatic image detectors. A model of the measured fingerprints explaining their features and classification performance, based on the polychromatic excitation of the indicators is proposed.Substantial amount of spectral information is retained in the fingerprints as corroborated by multivariate analysis and experimental

  6. Switched reluctance motor with DC assisted excitation

    Microsoft Academic Search

    Yue Li; Jerry D. Lloyd; Gary E. Horst

    1996-01-01

    A new topology of switched reluctance motor (SRM) drives is proposed in this paper. Based on a similar concept of the d q theory for conventional sinusoidal electric machines, this SRM with DC assisted excitation (SRDC) uses auxiliary DC windings to achieve the built-in field excitation in SRM structures. Since the field in this SRDC motor is established by the

  7. Excitation Mechanisms in Pulsed CO2 Lasers

    Microsoft Academic Search

    William B. McKnight; Redstone Arsenal; C. K. N. Patel

    1969-01-01

    Experimental studies were carried out on laser systems to investigate the excitation mechanisms of the upper laser level (0001) of carbon dioxide in an electrical discharge, and the parts played by helium and nitrogen in mixed systems. Used as constituent gases were carbon dioxide, carbon dioxide-nitrogen, and carbon dioxide-helium. Pulsed electrical excitation was used with an arrangement for varying the

  8. Continuous Microwave Excitation of Excimer Lamps

    Microsoft Academic Search

    Scott Bradley Hassal

    1991-01-01

    For decades, microwaves have been used to create gas discharges for many applications. This thesis deals with the use of microwaves to excite gas discharges for incoherent optical sources, with particular emphasis on excimer systems. In addition, microwave excitation of a gas laser is considered. A novel apparatus was designed and built to couple 2.45-GHz microwave radiation into a gas

  9. On Probabilistic Excitement of Sports Games

    Microsoft Academic Search

    Jan Vecer; Tomoyuki Ichiba; Mladen Laudanovic

    2007-01-01

    In this paper we introduce a quantitative measure of the excitement of sports games. This measure can be thought of as the variability of the expectancy of winning as a game progresses. We illustrate the concept of excitement at soccer games for which the theoretical win expectancy can be well approximated from a Poisson model of scoring. We show that

  10. Averaging in damping by parametric stiffness excitation

    Microsoft Academic Search

    Fadi Dohnal; Ferdinand Verhulst

    2007-01-01

    Stability investigations of vibration quenching employing the concept of actuators with a variable stiffness are pre- sented. Systems with an arbitrary number of degrees of freedom with linear spring- and damping-elements are considered, that are subject to self-excitation as well as parametric stiffness excitation. General conditions for full vibration suppression and conditions of instability are derived analytically by applying a

  11. Excitation equilibria in plasmas; a classification

    Microsoft Academic Search

    J. A. M. van der Mullen

    1990-01-01

    This review gives a classification of the excitation kinetics ruled by electrons in plasmas. It is a study on the atomic state distribution function (ASDF) and its relation with underlying processes, which, for the case of an electron excitation kinetics (EEK) plasma, is merely a competition between free and bound electrons, the same particles in different circumstances. In a quasi

  12. RXTE monitoring of the 65-ms X-ray Pulsars PSR J1811-1925 in G11.2-0.3, and PSR J0205+6559 in 3C 58

    NASA Astrophysics Data System (ADS)

    Gavriil, F. P.; Ransom, S. M.; Roberts, M. S. E.; Kaspi, V. M.; Gaensler, B. M.; Gotthelf, E. V.; Murray, S. S.; Slane, P. O.

    2003-03-01

    The X-ray Pulsars PSR J1811-1925 and PSR J0205+6559, in the historical supernova remnants G11.2-0.3 and 3C 58 respectively, have characteristic ages much greater than the ages of their remnants. This likely implies that their current spin periods, ˜65 ms, are close to their birth spin period. Alternatively, these pulsars may have unusually high braking indices. Despite the striking similarities in the pulsar's spin parameters and historical ages, the two have very different pulse shapes and X-ray luminosities, which could imply different emission mechanisms and/or geometries. We report here on regular Rossi X-ray Timing Explorer/ Proportional Counting Array (RXTE/PCA) timing observations of these pulsars that were designed to measure their braking indices. For PSR J1811-1925, we provide a preliminary phase-coherent timing solution which includes a significant ? ?. The braking index we measure is >> 3. This could be a manifestation of timing noise; further observations can test this. For PSR J0205+6559, excessive timing noise has made long-term phase coherent timing of this pulsar difficult, but preliminary results imply a braking index significantly greater than 3 as well. We also report on a preliminary analysis of the phase-averaged and phase-resolved spectra of both sources. This work is funded by NSERC, CIAR, NASA and a McGill University Tomlinson Fellowship.

  13. Hydrogen Bonding in the Electronic Excited State

    NASA Astrophysics Data System (ADS)

    Zhao, Guang-Jiu; Han, Ke-Li; DICP1101 Group Team

    2013-03-01

    Here, I will give a talk on our recent advances in electronic excited-state hydrogen-bonding dynamics and the significant role of excited-state hydrogen bonding on internal conversion (IC), electronic spectral shifts (ESS), photoinduced electron transfer (PET), fluorescence quenching (FQ), intramolecular charge transfer (ICT), and metal-to-ligand charge transfer (MLCT). The combination of various spectroscopic experiments with theoretical calculations has led to tremendous progress in excited-state hydrogen-bonding research. We first demonstrated that intermolecular hydrogen bond in excited state can be greatly strengthened or weakened for many chromophores. We have also clarified that intermolecular hydrogen-bond strengthening and weakening correspond to red-shifts and blue-shifts, respectively, in the electronic spectra. Moreover, radiationless deactivations (via IC, PET, ICT, MLCT, and so on) can be dramatically influenced by excited-state hydrogen bonding. Here, I will give a talk on our recent advances in electronic excited-state hydrogen-bonding dynamics and the significant role of excited-state hydrogen bonding on internal conversion (IC), electronic spectral shifts (ESS), photoinduced electron transfer (PET), fluorescence quenching (FQ), intramolecular charge transfer (ICT), and metal-to-ligand charge transfer (MLCT). The combination of various spectroscopic experiments with theoretical calculations has led to tremendous progress in excited-state hydrogen-bonding research. We first demonstrated that intermolecular hydrogen bond in excited state can be greatly strengthened or weakened for many chromophores. We have also clarified that intermolecular hydrogen-bond strengthening and weakening correspond to red-shifts and blue-shifts, respectively, in the electronic spectra. Moreover, radiationless deactivations (via IC, PET, ICT, MLCT, and so on) can be dramatically influenced by excited-state hydrogen bonding. GJZ and KLH thank the NSFC (Nos: 20903094 and 20833008) for financial support.

  14. College Of Engineering And Computer Science Laura J. Steinberg, Dean

    E-print Network

    Raina, Ramesh

    is to promote learning in engineering and computer science through integrated activities in teaching, researchCollege Of Engineering And Computer Science Laura J. Steinberg, Dean 227 Link Hall lcs.syr.edu/ About The College These are exciting times in engineering and computer science. Revolutionary changes

  15. 2010 Neutron Review: ORNL Neutron Sciences Progress Report

    Microsoft Academic Search

    Agatha A Bardoel; Deborah Melinda Counce; Allen E Ekkebus; Charlie M Horak; Stephen E Nagler; Lynn A Kszos

    2011-01-01

    During 2010, the Neutron Sciences Directorate focused on producing world-class science, while supporting the needs of the scientific community. As the instrument, sample environment, and data analysis tools at High Flux Isotope Reactor (HFIR ) and Spallation Neutron Source (SNS) have grown over the last year, so has promising neutron scattering research. This was an exciting year in science, technology,

  16. Inclination Excitation in Compact Extrasolar Planetary Systems

    NASA Astrophysics Data System (ADS)

    Becker, Juliette; Adams, Fred C.

    2015-05-01

    The Kepler Mission has detected dozens of compact planetary systems with more than four transiting planets. This sample provides a collection of close-packed planetary systems with relatively little spread in the inclination angles of the inferred orbits. We have explored the effectiveness of dynamical mechanisms in exciting orbital inclination in this class of solar systems. The two mechanisms we discuss are self-excitation of orbital inclination in initially (nearly) coplanar planetary systems and perturbations by additional unseen larger bodies in the outer regions of the solar systems. For both of these scenarios, we determine the regimes of parameter space for which orbital inclination can be effectively excited. For compact planetary systems with the observed architectures, we find that the orbital inclination angles are not spread out appreciably through self-excitation, resulting in a negligible scatter in impact parameter and a subsequently stable transiting system. In contrast, companions in the outer solar system can be effective in driving variations of the inclination angles of the inner planetary orbits, leading to significant scatter in impact parameter and resultantly non-transiting systems. We present the results of our study, the regimes in which each excitation method - self-excitation of inclination and excitation by a perturbing secondary - are relevant, and the magnitude of the effects.

  17. Earth Sciences Environmental Earth Sciences,

    E-print Network

    Brierley, Andrew

    94 Earth Sciences­ Environmental Earth Sciences, Geology Degree options MGeol (Single Honours Degrees) Earth Sciences BSc (Single Honours Degrees) Environmental Earth Sciences Geology BSc (Joint placement. * The Geology and Environmental Earth Sciences degrees are accredited by the Geological Society

  18. Pulse Vector-Excitation Speech Encoder

    NASA Technical Reports Server (NTRS)

    Davidson, Grant; Gersho, Allen

    1989-01-01

    Proposed pulse vector-excitation speech encoder (PVXC) encodes analog speech signals into digital representation for transmission or storage at rates below 5 kilobits per second. Produces high quality of reconstructed speech, but with less computation than required by comparable speech-encoding systems. Has some characteristics of multipulse linear predictive coding (MPLPC) and of code-excited linear prediction (CELP). System uses mathematical model of vocal tract in conjunction with set of excitation vectors and perceptually-based error criterion to synthesize natural-sounding speech.

  19. Elementary excitations of sup 4 He clusters

    SciTech Connect

    Casas, M. (Universitat de les Illes Balears, Palma de Mallorca (Spain)); Stringari, S. (Universita di Trento, Povo (Italy))

    1990-05-01

    The elementary excitations of {sup 4}He clusters containing N atoms are investigated by solving the equations of the random phase approximation (RPA) with a phenomenological effective interaction. The calculations were done for 40{le}N{le}728. The effects of the RPA correlations are explicitly discussed. Important deviations from the predictions of the liquid droplet model (LDM) are found up to N{approx equal}500 for the breathing compression mode and up to N{approx equal}100 for surface excitations. Sum rules for compression and surface excitations are also derived and discussed.

  20. An observation concerning electronically excited retinal

    PubMed Central

    Simons, Jack

    1977-01-01

    The observation of Mathies and Stryer of highly polar excited electronic states of all-trans-retinal, its unprotonated Schiff base, a salt of the protonated Schiff base, and 11-cis-retinal leads us to propose a possible consequence of the existence of such species. The highly polar excited molecule may have sufficient potential to oxidize its surroundings, thus achieving a transfer of one electron. Experimental evidence is combined with crude model calculations to support the possible role of these excited states as electron transfer agents. PMID:16592429

  1. SCIENCE CHINA Technological Sciences

    E-print Network

    Simons, Jack

    SCIENCE CHINA Technological Sciences © Science China Press and Springer-Verlag Berlin Heidelberg. Density-functional-theory formulation of classical and quantum Hooke's law. Sci China Tech Sci, 2014, 57- sider an equilibrium lattice without strain (=0), but elec- #12;Hu H, et al. Sci China Tech Sci April

  2. Seismic excitation by space shuttles

    USGS Publications Warehouse

    Kanamori, H.; Mori, J.; Sturtevant, B.; Anderson, D.L.; Heaton, T.

    1992-01-01

    Shock waves generated by the space shuttles Columbia (August 13, 1989), Atlantis (April 11, 1991) and Discovery (September 18, 1991) on their return to Edwards Air Force Base, California, were recorded by TERRAscope (Caltech's broadband seismic network), the Caltech-U.S.G.S Southern California Seismic Network (SCSN), and the University of Southern California (USC) Los Angeles Basin Seismic Network. The spatial pattern of the arrival times exhibits hyperbolic shock fronts from which the path, velocity and altitude of the space shuttle could be determined. The shock wave was acoustically coupled to the ground, converted to a seismic wave, and recorded clearly at the broadband TERRAscope stations. The acoustic coupling occurred very differently depending on the conditions of the Earth's surface surrounding the station. For a seismic station located on hard bedrock, the shock wave (N wave) was clearly recorded with little distortion. Aside from the N wave, very little acoustic coupling of the shock wave energy to the ground occurred at these sites. The observed N wave record was used to estimate the overpressure of the shock wave accurately; a pressure change of 0.5 to 2.2 mbars was obtained. For a seismic station located close to the ocean or soft sedimentary basins, a significant amount of shock wave energy was transferred to the ground through acoustic coupling of the shock wave and the oceanic Rayleigh wave. A distinct topography such as a mountain range was found effective to couple the shock wave energy to the ground. Shock wave energy was also coupled to the ground very effectively through large man made structures such as high rise buildings and offshore oil drilling platforms. For the space shuttle Columbia, in particular, a distinct pulse having a period of about 2 to 3 seconds was observed, 12.5 s before the shock wave, with a broadband seismograph in Pasadena. This pulse was probably excited by the high rise buildings in downtown Los Angeles which were simultaneously hit by the space shuttle shock waves. The proximity of the natural periods of the high rise buildings and the modal periods of the Los Angeles basin enabled efficient energy transfer from shock wave to seismic wave. ?? 1992 Springer-Verlag.

  3. Acoustics of Excited Jets: A Historical Perspective

    NASA Technical Reports Server (NTRS)

    Brown, Cliffard A.

    2005-01-01

    The idea that a jet may be excited by external forcing is not new. The first published demonstration of a jet responding to external pressure waves occurred in the mid-1800's. It was not, however, until the 1950's, with the advent of commercial jet aircraft, that interest in the subject greatly increased. Researchers first used excited jets to study the structure of the jet and attempt to determine the nature of the noise sources. The jet actuators of the time limited the range (Reynolds and Mach numbers) of jets that could be excited. As the actuators improved, more realistic jets could be studied. This has led to a better understanding of how jet excitation may be used not only as a research tool to understand the flow properties and noise generation process, but also as a method to control jet noise.

  4. Rotational excitation of CH+ by electron impact

    E-print Network

    Chu, Shih-I; Dalgarno, A.

    1974-09-01

    The cross sections for the rotational excitation of polar diatomic molecular ions by electron impact are formulated within the Coulomb-Born approximation. The cross sections are finite at threshold. Explicit calculations are reported...

  5. Nuclear excitation by electronic transition (NEET).

    SciTech Connect

    Ahmad, I.; Dunford, R. W.; Esbensen, H.; Gemmell, D. S.; Kanter, E. P.; Kraessig, B.; Ruett, U.; Southworth, S. H.

    1999-04-28

    We present a report on recent measurements using the Advanced Photon Source at Argonne National Laboratory to explore the phenomenon of Nuclear Excitation by Electronic Transition (NEET) in the {sup 189}Os atomic/nuclear system.

  6. Dissociative Excitation of Thymine by Electron Impact

    NASA Astrophysics Data System (ADS)

    McConkey, William; Tiessen, Collin; Hein, Jeffrey; Trocchi, Joshuah; Kedzierski, Wladek

    2014-05-01

    A crossed electron-gas beam system coupled to a VUV spectrometer has been used to investigate the dissociation of thymine (C5H6N2O2) into excited atomic fragments in the electron-impact energy range from threshold to 375 eV. A special stainless steel oven is used to vaporize the thymine and form it into a beam where it is intersected by a magnetically collimated electron beam, typical current 50 ?A. The main features in the spectrum are the H Lyman series lines. The probability of extracting excited C or N atoms from the ring is shown to be very small. In addition to spectral data, excitation probability curves as a function of electron energy will be presented for the main emission features. Possible dissociation channels and excitation mechanisms in the parent molecule will be discussed. The authors thank NSERC (Canada) for financial support.

  7. "Safe" Coulomb Excitation of 30Mg

    E-print Network

    O. Niedermaier; H. Scheit; V. Bildstein; H. Boie; J. Fitting; R. von Hahn; F. K"ock; M. Lauer; U. K. Pal; H. Podlech; R. Repnow; D. Schwalm

    2004-12-17

    We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy of 2.25 MeV/u together with a thin nat-Ni target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative de-excitation gamma ray yields the B(E2; 0+ -> 2+) value of 30Mg was determined to be 241(31) e2fm4. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope 30Mg lies still outside the ``island of inversion''.

  8. Faraday Waves under Time-Reversed Excitation

    NASA Astrophysics Data System (ADS)

    Pietschmann, Dirk; Stannarius, Ralf; Wagner, Christian; John, Thomas

    2013-03-01

    Do parametrically driven systems distinguish periodic excitations that are time mirrors of each other? Faraday waves in a Newtonian fluid are studied under excitation with superimposed harmonic wave forms. We demonstrate that the threshold parameters for the stability of the ground state are insensitive to a time inversion of the driving function. This is a peculiarity of some dynamic systems. The Faraday system shares this property with standard electroconvection in nematic liquid crystals [J. Heuer , Phys. Rev. E 78, 036218 (2008)PLEEE81539-3755]. In general, time inversion of the excitation affects the asymptotic stability of a parametrically driven system, even when it is described by linear ordinary differential equations. Obviously, the observed symmetry has to be attributed to the particular structure of the underlying differential equation system. The pattern selection of the Faraday waves above threshold, on the other hand, discriminates between time-mirrored excitation functions.

  9. Ultrafast optical excitation of magnetic skyrmions

    NASA Astrophysics Data System (ADS)

    Ogawa, N.; Seki, S.; Tokura, Y.

    2015-04-01

    Magnetic skyrmions in an insulating chiral magnet Cu2OSeO3 were studied by all-optical spin wave spectroscopy. The spins in the conical and skyrmion phases were excited by the impulsive magnetic field from the inverse-Faraday effect, and resultant spin dynamics were detected by using time-resolved magneto-optics. Clear dispersions of the helimagnon were observed, which is accompanied by a distinct transition into the skyrmion phase, by sweeping temperature and magnetic field. In addition to the collective excitations of skyrmions, i.e., rotation and breathing modes, several spin precession modes were identified, which would be specific to optical excitation. The ultrafast, nonthermal, and local excitation of the spin systems by photons would lead to the efficient manipulation of nano-magnetic structures.

  10. Nonlinear excited waves on the interventricular septum

    NASA Astrophysics Data System (ADS)

    Bekki, Naoaki; Harada, Yoshifumi; Kanai, Hiroshi

    2012-11-01

    Using a novel ultrasonic noninvasive imaging method, we observe some phase singularities in propagating excited waves on a human cardiac interventricular septum (IVS) for a healthy young male. We present a possible physical model explaining one-dimensional dynamics of phase singularities in nonlinearly excited waves on the IVS. We show that at least one of the observed phase singularities in the excited waves on the IVS can be explained by the Bekki-Nozaki hole solution of the complex Ginzburg-Landau equation without any adjustable parameters. We conclude that the complex Ginzburg-Landau equation is such a suitable model for one-dimensional dynamics of cardiac phase singularities in nonlinearly excited waves on the IVS.

  11. Ultrafast optical excitation of magnetic skyrmions.

    PubMed

    Ogawa, N; Seki, S; Tokura, Y

    2015-01-01

    Magnetic skyrmions in an insulating chiral magnet Cu2OSeO3 were studied by all-optical spin wave spectroscopy. The spins in the conical and skyrmion phases were excited by the impulsive magnetic field from the inverse-Faraday effect, and resultant spin dynamics were detected by using time-resolved magneto-optics. Clear dispersions of the helimagnon were observed, which is accompanied by a distinct transition into the skyrmion phase, by sweeping temperature and magnetic field. In addition to the collective excitations of skyrmions, i.e., rotation and breathing modes, several spin precession modes were identified, which would be specific to optical excitation. The ultrafast, nonthermal, and local excitation of the spin systems by photons would lead to the efficient manipulation of nano-magnetic structures. PMID:25897634

  12. Mode Selective Excitation Using Coherent Control Spectroscopy

    SciTech Connect

    Singh, Ajay K. [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai-400094 (India); School of Engineering and Science, Jacobs University Bremen, Bremen, 28759 (Germany); Konradi, Jakow; Materny, Arnulf [School of Engineering and Science, Jacobs University Bremen, Bremen, 28759 (Germany); Sarkar, Sisir K. [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai-400094 (India)

    2008-11-14

    Femtosecond time-resolved coherent anti-Stokes Raman scattering (fs-CARS) gives access to ultrafast molecular dynamics. However, femtosecond laser pulses are spectrally broad and therefore coherently excite several molecular modes. While the temporal resolution is high, usually no mode-selective excitation is possible. This paper demonstrates the feasibility of selectively exciting specific molecular vibrations in solution phase with shaped fs laser excitation using a feedback-controlled optimization technique guided by an evolutionary algorithm. This approach is also used to obtain molecule-specific CARS spectra from a mixture of different substances. The optimized phase structures of the fs pulses are characterized to get insight into the control process. Possible applications of the spectrum control are discussed.

  13. Adaptive excitation control in power systems 

    E-print Network

    Chiu, Pei-Chen

    2006-08-16

    This thesis presents an adaptive excitation controller of power systems. The control law is derived by using model reference adaptive control (MRAC) or adaptive pole placement control (APPC) and an equilibrium tracking ...

  14. Science Sampler: Developing the scientist in your students

    NSDL National Science Digital Library

    Mary Hatton

    2006-01-01

    Develop the budding scientist within your students by weaving this hands-on, exciting project into your science curriculum. This inquiry-based project allows students to design, carry out, annalyze, and communicate their findings to their peers while havi

  15. Students Excited by Stellar Discovery

    NASA Astrophysics Data System (ADS)

    2011-02-01

    In the constellation of Ophiuchus, above the disk of our Milky Way Galaxy, there lurks a stellar corpse spinning 30 times per second -- an exotic star known as a radio pulsar. This object was unknown until it was discovered last week by three high school students. These students are part of the Pulsar Search Collaboratory (PSC) project, run by the National Radio Astronomy Observatory (NRAO) in Green Bank, WV, and West Virginia University (WVU). The pulsar, which may be a rare kind of neutron star called a recycled pulsar, was discovered independently by Virginia students Alexander Snider and Casey Thompson, on January 20, and a day later by Kentucky student Hannah Mabry. "Every day, I told myself, 'I have to find a pulsar. I better find a pulsar before this class ends,'" said Mabry. When she actually made the discovery, she could barely contain her excitement. "I started screaming and jumping up and down." Thompson was similarly expressive. "After three years of searching, I hadn't found a single thing," he said, "but when I did, I threw my hands up in the air and said, 'Yes!'." Snider said, "It actually feels really neat to be the first person to ever see something like that. It's an uplifting feeling." As part of the PSC, the students analyze real data from NRAO's Robert C. Byrd Green Bank Telescope (GBT) to find pulsars. The students' teachers -- Debra Edwards of Sherando High School, Leah Lorton of James River High School, and Jennifer Carter of Rowan County Senior High School -- all introduced the PSC in their classes, and interested students formed teams to continue the work. Even before the discovery, Mabry simply enjoyed the search. "It just feels like you're actually doing something," she said. "It's a good feeling." Once the pulsar candidate was reported to NRAO, Project Director Rachel Rosen took a look and agreed with the young scientists. A followup observing session was scheduled on the GBT. Snider and Mabry traveled to West Virginia to assist in the follow-up observations, and Thompson joined online. "Observing with the students is very exciting. It gives the students a chance to learn about radio telescopes and pulsar observing in a very hands-on way, and it is extra fun when we find a pulsar," said Rosen. Snider, on the other hand, said, "I got very, very nervous. I expected when I went there that I would just be watching other people do things, and then I actually go to sit down at the controls. I definitely didn't want to mess something up." Everything went well, and the observations confirmed that the students had found an exotic pulsar. "I learned more in the two hours in the control room than I would have in school the whole day," Mabry said. Pulsars are spinning neutron stars that sling lighthouse beams of radio waves or light around as they spin. A neutron star is what is left after a massive star explodes at the end of its normal life. With no nuclear fuel left to produce energy to offset the stellar remnant's weight, its material is compressed to extreme densities. The pressure squeezes together most of its protons and electrons to form neutrons; hence, the name neutron star. One tablespoon of material from a pulsar would weigh 10 million tons -- as much as a supertanker. The object that the students discovered is in a special class of pulsar that spins very fast - in this case, about 30 times per second, comparable to the speed of a kitchen blender. "The big question we need to answer first is whether this is a young pulsar or a recycled pulsar," said Maura McLaughlin, an astronomer at WVU. "A pulsar spinning that fast is very interesting as it could be newly born or it could be a very old, recycled pulsar." A recycled pulsar is one that was once in a binary system. Material from the companion star is deposited onto the pulsar, causing it to speed up, or be recycled. Mystery remains, however, about whether this pulsar has ever had a companion star. If it did, "it may be t

  16. Excitation of Be + by electron impact

    Microsoft Academic Search

    P. S. Ganas; L. P. Gately

    1983-01-01

    A realistic analytic central potential is used to generate wave functions for the ground and excited states of singly-ionized beryllium. Generalized oscillator strengths and integrated cross sections from threshold to 5 keV are calculated in the Born approximation for 2s-ns, 2s-np and 2s-nd excitations. Comparison of the cross sections with experimental and theoretical data is discussed for the 2s-2p transition.

  17. Evolution of locally excited avalanches in semiconductors

    E-print Network

    Z. L. Yuan; J. F. Dynes; A. W. Sharpe; A. J. Shields

    2010-05-25

    We show that semiconductor avalanche photodiodes can exhibit diminutive amplification noise during the early evolution of avalanches. The noise is so low that the number of locally excited charges that seed each avalanche can be resolved. These findings constitute an important first step towards realization of a solid-state noiseless amplifier. Moreover, we believe that the experimental setup used, \\textit{i.e.}, time-resolving locally excited avalanches, will become a useful tool for optimizing the number resolution.

  18. Gamow-Teller strength at high excitations

    Microsoft Academic Search

    G. F. Bertsch; I. Hamamoto

    1982-01-01

    A perturbative calculation is reported for the mixing of Gamow-Teller strength with two-particle two-hole configurations at high excitation energies. We find that roughly 50% of the Gamow-Teller strength is shifted into the region of 10--45 MeV excitation for the nucleus ⁹°Zr. This would explain a substantial part of the continuum background seen in the 200 MeV (p,n) reaction.

  19. Low-lying collective excitations in

    NASA Astrophysics Data System (ADS)

    Zimmerman, James Aaron

    2000-09-01

    The unstable nuclei 18Fg.s. and 18Fm have been studied via intermediate-energy Coulomb excitation in an attempt to populate collective states above the short-lived 18Fm 1.1 MeV (J? = 5+) isomeric (t1/2 = 162 ns) state. A radioactive beam of 18F and 18Fm nuclei was produced by nucleon transfer to energies per nucleon (E/A) of 40 MeV/u, delivered to a 197Au target for Coulomb-excitation. Photons emitted in the vicinity of the 197 Au target were detected in a large-angle NaI(Tl) array, which allowed for the identification of the excited states populated by intermediate-energy Coulomb excitation. Upper limits were established for reduced transition probabilities B(E2; 5+ --> 4+,3+) of several predicted transitions from the 18Fm isomeric state. The reduced transition strengths, B(E? ? ), of two 18F ground state excitations were also directly measured via intermediate-energy Coulomb excitation for the first time. The energies and B(E? ? ; 1+g.s. --> 2+2523,2-2101 ) values for these transitions are reported. An indication of enhanced isomer decay, possibly due to the Coulomb interaction with the target is seen and discussed.

  20. Adjustable, Broadband, Selective Excitation with Uniform Phase

    NASA Astrophysics Data System (ADS)

    Cano, Kristin E.; Smith, Mari A.; Shaka, A. J.

    2002-03-01

    An advance in the problem of achieving broadband, selective, and uniform-phase excitation in NMR spectroscopy of liquids is outlined. Broadband means that, neglecting relaxation, any frequency bandwidth may be excited even when the available radiofrequency (RF) field strength is strictly limited. Selective means that sharp transition edges can be created between pure-phase excitation and no excitation at all. Uniform phase means that, neglecting spin-spin coupling, all resonance lines have nearly the same phase. Conventional uniform-phase excitation pulses (e.g., E-BURP), mostly based on amplitude modulation of the RF field, are not broadband: they have an achievable bandwidth that is strictly limited by the peak power available. Other compensated pulses based on adiabatic half-passage, like BIR-4, are not selective. By contrast, inversion pulses based on adiabatic fast passage can be broadband (and selective) in the sense above. The advance outlined is a way to reformulate these frequency modulated (FM) pulses for excitation, rather than just inversion.

  1. Adjustable, broadband, selective excitation with uniform phase.

    PubMed

    Cano, Kristin E; Smith, Mari A; Shaka, A J

    2002-03-01

    An advance in the problem of achieving broadband, selective, and uniform-phase excitation in NMR spectroscopy of liquids is outlined. Broadband means that, neglecting relaxation, any frequency bandwidth may be excited even when the available radiofrequency (RF) field strength is strictly limited. Selective means that sharp transition edges can be created between pure-phase excitation and no excitation at all. Uniform phase means that, neglecting spin-spin coupling, all resonance lines have nearly the same phase. Conventional uniform-phase excitation pulses (e.g., E-BURP), mostly based on amplitude modulation of the RF field, are not broadband: they have an achievable bandwidth that is strictly limited by the peak power available. Other compensated pulses based on adiabatic half-passage, like BIR-4, are not selective. By contrast, inversion pulses based on adiabatic fast passage can be broadband (and selective) in the sense above. The advance outlined is a way to reformulate these frequency modulated (FM) pulses for excitation, rather than just inversion. PMID:11945042

  2. Connecting Science and Literacy in the Classroom: Using Space and Earth Science to Support Language Arts

    NASA Astrophysics Data System (ADS)

    Wessen, A. S.; Cobabe-Ammann, E. A.

    2009-12-01

    The connections between science and literacy in the classroom have received increasing attention over the last two decades, as more and more evidence demonstrates that science provides an exciting vehicle in which to engage students on the path to literacy improvement. Combining literacy with science allows students to creatively explore the world or universe, and it. Combining science and literacy improves both reading and science scores, and increases students’ interest in science. At a time when over 40% of students beyond the 5th grade are reading two or more levels below grade level and are struggling with their current materials, finding ways to excite and engage them in the reading process is key. Literacy programs incorporating unique space science content can help prepare children for standardized language arts tests. It also engages our nation’s youngest learners and their teachers with the science, math, and technology of exploration in a language arts format. This session focuses on programs and products that bring the excitement of earth and space science into the literacy classroom, with a focus on research-based approached to combining science and language arts. Reading, Writing and Rings! Grades 1-2

  3. Everyone Loves Science

    NASA Astrophysics Data System (ADS)

    Selen, Mats

    2014-03-01

    Twenty years ago we started a small outreach program at the University of Illinois called ``The Physics Van,'' designed to show the fun of science to assemblies of kids at local elementary schools. Many hundreds of shows - and many hundreds of thousands of excited kids, teachers, and parents later - the program is a cornerstone of the department's outreach efforts. About fourteen years ago I stumbled into a one-time gig with the local CBS television station, which evolved into a weekly live science segment on their morning news show. Very popular with viewers across central Illinois, these science segments now include a colleague from the Department of Chemistry and cover a wide range of topics. The totally unexpected success of both has led me to ponder why these seemingly hapless efforts should have grown to be both successful and sustainable. The conclusions, I believe, are very good news for us all.

  4. ALMA imaging study of methyl formate (HCOOCH$_{3}$) in the torsionally excited states towards Orion KL

    E-print Network

    Sakai, Yusuke; Hirota, Tomoya

    2015-01-01

    We recently reported the first identification of rotational transitions of methyl formate (HCOOCH$_{3}$) in the second torsionally excited state toward Orion Kleinmann-Low (KL) observed with the Nobeyama 45 m telescope. In combination with the identified transitions of methyl formate in the ground state and the first torsional excited state, it was found that there is a difference in rotational temperature and vibrational temperature, where the latter is higher. In this study, high spatial resolution analysis by using Atacama Large Millimeter/Submillimeter Array (ALMA) science verification data was carried out to verify and understand this difference. Toward the Compact Ridge, two different velocity components at 7.3 and 9.1 km s$^{-1}$ were confirmed, while a single component at 7.3 km s$^{-1}$ was identified towards the Hot Core. The intensity maps in the ground, first, and second torsional excited states have quite similar distributions. Using extensive ALMA data, we determined the rotational and vibration...

  5. Electron impact excitation of xenon from the metastable state to the excited states

    Microsoft Academic Search

    Jun Jiang; Chen-Zhong Dong; Lu-You Xie; Xiao-Xin Zhou; Jian-Guo Wang

    2008-01-01

    The electron impact excitation cross sections from the lowest metastable state 5p56sJ = 2 to the six lowest excited states of the 5p56p configuration of xenon are calculated systematically by using the fully relativistic distorted wave method. In order to discuss the effects of target state descriptions on the electron impact excitation cross sections, two correlation models are used to

  6. Science Sampler: Making movies in the classroom

    NSDL National Science Digital Library

    Lauren Richards

    2006-07-01

    When you overhear students talking excitedly about video games, the internet, television, or movies, do you ever wish that they could get that excited about what was happening in the science classroom? By using simple software, students can plan, shoot, and edit movies of their own design! In this fascinating activity, students create a documentary on a famous earthquake, volcanic eruption, tsunami, hurricane, or other natural disaster as they put their own unique spin on the theory of plate tectonics.

  7. Practicing Science: The Investigative Approach in College Science Teaching

    NSDL National Science Digital Library

    NSTA Press

    2001-01-01

    In this collection of ten articles reprinted from the Journal of College Science Teaching, college and university science professors show how they have used investigative learning--or inquiry-based instruction--to introduce students to the process of science. These first-person accounts demonstrate how students, including non-science majors, can learn to do science as it is done in the real world--through hypothesis building, observation, and experimental design. The higher education faculty represented in this book is committed to the investigative approach. As one contributor writes, "Would I return to lecturing in a traditional fashion? Not a chance. The excitement and energy of a room of students working in groups, challenging each other, and questioning each other is what I'll always want to see in my classroom."

  8. Förster excitation energy transfer in peridinin-chlorophyll-a-protein.

    PubMed Central

    Kleima, F J; Hofmann, E; Gobets, B; van Stokkum, I H; van Grondelle, R; Diederichs, K; van Amerongen, H

    2000-01-01

    Time-resolved fluorescence anisotropy spectroscopy has been used to study the chlorophyll a (Chl a) to Chl a excitation energy transfer in the water-soluble peridinin-chlorophyll a-protein (PCP) of the dinoflagellate Amphidinium carterae. Monomeric PCP binds eight peridinins and two Chl a. The trimeric structure of PCP, resolved at 2 A (, Science. 272:1788-1791), allows accurate calculations of energy transfer times by use of the Förster equation. The anisotropy decay time constants of 6.8 +/- 0.8 ps (tau(1)) and 350 +/- 15 ps (tau(2)) are respectively assigned to intra- and intermonomeric excitation equilibration times. Using the ratio tau(1)/tau(2) and the amplitude of the anisotropy, the best fit of the experimental data is achieved when the Q(y) transition dipole moment is rotated by 2-7 degrees with respect to the y axis in the plane of the Chl a molecule. In contrast to the conclusion of, Biochemistry. 23:1564-1571) that the refractive index (n) in the Förster equation should be equal to that of the solvent, n can be estimated to be 1.6 +/- 0.1, which is larger than that of the solvent (water). Based on our observations we predict that the relatively slow intermonomeric energy transfer in vivo is overruled by faster energy transfer from a PCP monomer to, e.g., the light-harvesting a/c complex. PMID:10620298

  9. Molecular rotational excitation by strong femtosecond laser pulses.

    PubMed

    Wu, Chengyin; Zeng, Guiping; Jiang, Hongyan; Gao, Yunan; Xu, Nan; Gong, Qihuang

    2009-10-01

    We study the rotational wave packet created by nonadiabatic rotational excitation of molecules with strong femtosecond laser pulses. The applicable condition of the Delta-Kick method is obtained by comparing the laser intensity and pulse duration dependences of the wave packet calculated with different methods. The wave packet evolution is traced analytically with the Delta-Kick method. The calculations demonstrate that the rotational populations can be controlled for the rotational wave packet created by two femtosecond laser pulses. The evolution of the rotational wave packet with controlled populations produces interference patterns with exotic spatial symmetries. These calculations are validated by comparing the theoretical calculations with our experimental measurements for the rotational wave packet created by thermal ensemble CO(2) and two strong femtosecond laser pulses. Potential applications in molecular science are also discussed for the rotational wave packet with controlled populations and spatial symmetries. PMID:19746946

  10. Molecular Rotational Excitation by Strong Femtosecond Laser Pulses

    NASA Astrophysics Data System (ADS)

    Wu, Chengyin; Zeng, Guiping; Jiang, Hongyan; Gao, Yunan; Xu, Nan; Gong, Qihuang

    2009-09-01

    We study the rotational wave packet created by nonadiabatic rotational excitation of molecules with strong femtosecond laser pulses. The applicable condition of the Delta-Kick method is obtained by comparing the laser intensity and pulse duration dependences of the wave packet calculated with different methods. The wave packet evolution is traced analytically with the Delta-Kick method. The calculations demonstrate that the rotational populations can be controlled for the rotational wave packet created by two femtosecond laser pulses. The evolution of the rotational wave packet with controlled populations produces interference patterns with exotic spatial symmetries. These calculations are validated by comparing the theoretical calculations with our experimental measurements for the rotational wave packet created by thermal ensemble CO2 and two strong femtosecond laser pulses. Potential applications in molecular science are also discussed for the rotational wave packet with controlled populations and spatial symmetries.

  11. Excitation Mechanisms of RE Ions in Semiconductors

    NASA Astrophysics Data System (ADS)

    Braud, Alain

    This chapter presents an overview of the mechanisms responsible for the excitation of optically active rare-earth (RE) ions in semiconductors. Besides resonant excitation of the RE 4f shell, several non-resonant processes can take place in which the host is excited first. These indirect mechanisms involve nonradiative transfer of the recombination energy of electrons and holes to nearby RE ions. Distinct excitation processes arise because of the various conditions under which the electron may recombine with a hole. The different possibilities are presented and discussed in the first part of this chapter. Carriers of opposite charge bind to each other to form either a free exciton or a trapped (bound) exciton. In the latter case, the trapping can arise from the incorporation of RE ions which induces distortions of the host lattice. The exciton trapping can also be due to an impurity, a local defect or even an extended defect. Other possible mechanisms involve the capture of an electron by the 5d shell changing the valence state from trivalent to divalent with the subsequent capture of a hole. Finally, the role of impurities associated with donor-acceptor pairs in the recombination of electrons and holes with energy transfer to RE ions is discussed. In the second part of this chapter the specific case of RE-doped GaN is considered. Results are presented to show that local defects play a major role in the excitation process by binding excitons with a subsequent energy transfer to RE ions. A general modelling of the RE excitation mechanism mediated by bound excitons (BE) is presented and discussed. Finally, experiments using two excitation sources are shown to give valuable information concerning the RE-related defects.

  12. Tone-excited jet: Theory and experiments

    NASA Technical Reports Server (NTRS)

    Ahuja, K. K.; Lepicovsky, J.; Tam, C. K. W.; Morris, P. J.; Burrin, R. H.

    1982-01-01

    A detailed study to understand the phenomenon of broadband jet-noise amplification produced by upstream discrete-tone sound excitation has been carried out. This has been achieved by simultaneous acquisition of the acoustic, mean velocity, turbulence intensities, and instability-wave pressure data. A 5.08 cm diameter jet has been tested for this purpose under static and also flight-simulation conditions. An open-jet wind tunnel has been used to simulate the flight effects. Limited data on heated jets have also been obtained. To improve the physical understanding of the flow modifications brought about by the upstream discrete-tone excitation, ensemble-averaged schlieren photographs of the jets have also been taken. Parallel to the experimental study, a mathematical model of the processes that lead to broadband-noise amplification by upstream tones has been developed. Excitation of large-scale turbulence by upstream tones is first calculated. A model to predict the changes in small-scale turbulence is then developed. By numerically integrating the resultant set of equations, the enhanced small-scale turbulence distribution in a jet under various excitation conditions is obtained. The resulting changes in small-scale turbulence have been attributed to broadband amplification of jet noise. Excellent agreement has been found between the theory and the experiments. It has also shown that the relative velocity effects are the same for the excited and the unexcited jets.

  13. Targeting individual excited states in DMRG.

    NASA Astrophysics Data System (ADS)

    Dorando, Jonathan; Hachmann, Johannes; Kin-Lic Chan, Garnet

    2007-03-01

    The low-lying excited states of ?-conjugated molecules are important for the development of novel devices such as lasers, light-emitting diodes, photovoltaic cells, and field-effect transistors [1,2]. The ab-intio Density Matrix Renormalization Group (DMRG) provides a powerful way to explore the electronic structure of quasi-one-dimensional systems such as conjugated organic oligomers. However, DMRG is limited to targeting only low-lying excited states through state-averaged DMRG (SDMRG). There are several drawbacks; state-averaging degrades the accuracy of the excited states and is limited to at most a few of the low-lying states [3]. In this study, we present a new method for targeting higher individual excited states. Due to progress in the field of numerical analysis presented by Van Der Horst and others [4], we are able to target individual excited states of the Hamiltonian. This is accomplished by modifying the Jacobi-Davidson algorithm via a ``Harmonic Ritz'' procedure. We will present studies of oligoacenes and polyenes that compare the accuracy of SDMRG and Harmonic Davidson DMRG. [1] Burroughes, et al. , Nature 347, 539 (1990). [2] Shirota, J. Mater. Chem. 10, 1, (2000). [3] Ramasesha, Pati, Krishnamurthy, Shuai, Bredas, Phys. Rev. B. 54, 7598, (1997). [4] Bai, Demmel, Dongarra, Ruhe, Van Der Horst, Templates for the Solution of Algebraic Eigenvalue Problems, SIAM, 2000.

  14. Photoionization dynamics of excited molecular states

    NASA Astrophysics Data System (ADS)

    Dehmer, J. L.; Ohalloran, M. A.; Tomkins, F. S.; Dehmer, P. M.; Pratt, S. T.

    Resonance Enhanced Multiphoton Ionization (REMPI) utilizes tunable dye lasers to ionize an atom or molecule by first preparing an excited state by multiphoton absorption and then ionizing that state before it can decay. This process is highly selective with respect to both the initial and resonant intermediate states of the target, and it can be extremely sensitive. In addition, the products of the REMPI process can be detected as needed by analyzing the resulting electrons, ions, fluorescence, or by additional REMPI. This points to a number of opportunities for exploring excited state physics and chemistry at the quantum-state-specific level. Here we will first give a brief overview of the large variety of experimental approaches to excited state phenomena made possible by REMPI. Then we will examine in more detail, recent studies of the three photon resonant, four photon (3 + 1) ionization of H sub 2 via the C(I) sub pi sub u state. Strong non-Franck-Condon behavior in the photoelectron spectra of this nominally simple Rydberg state has led to the examination of a variety of dynamical mechanisms. Of these, the role of doubly excited autoionizing states now seems decisive. Progress on photoelectron studies of autoionizing states in H sub 2 , excited in a (2 + 1) REMPI process via the E,F(I) sub sigma plus sub g will also be briefly discussed.

  15. Electronically excited states of PANH anions.

    PubMed

    Theis, Mallory L; Candian, Alessandra; Tielens, Alexander G G M; Lee, Timothy J; Fortenberry, Ryan C

    2015-05-27

    The singly deprotonated anion derivatives of nitrogenated polycyclic aromatic hydrocarbons (PANHs) are investigated for their electronically excited state properties. These include single deprotonation of the two unique arrangements of quinoline producing fourteen different isomers. This same procedure is also undertaken for single deprotonation of the three nitrogenation isomers of acridine and the three of pyrenidine. It is shown quantum chemically that the quinoline-class of PANH anion derivatives can only produce a candidate dipole-bound excited state each, a state defined as the interaction of an extra electron with the dipole moment of the corresponding neutral. However, the acridine- and pyrenidine-classes possess valence excited states as well as the possible dipole-bound excited states where the latter is only possible if the dipole moment is sufficiently large to retain the extra electron; the valence excitation is independent of the radical dipolar strength. As a result, the theoretical vertically computed electronic spectra of deprotonated PANH anion derivatives is fairly rich in the 1.5 eV to 2.5 eV range significantly opening the possibilities for these molecules to be applied to longer wavelength studies of visible and near-IR spectroscopy. Lastly, the study of these systems is also enhanced by the inclusion of informed orbital arrangements in a simply constructed basis set that is shown to be more complete and efficient than standard atom-centered functions. PMID:25975430

  16. Excited level populations and excitation kinetics of nonequilibrium ionizing argon discharge plasma of atmospheric pressure

    SciTech Connect

    Akatsuka, Hiroshi [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1-N1-10, O-Okayama, Meguro-ku, Tokyo 152-8550 (Japan)

    2009-04-15

    Population densities of excited states of argon atoms are theoretically examined for ionizing argon plasma in a state of nonequilibrium under atmospheric pressure from the viewpoint of elementary processes with collisional radiative model. The dependence of excited state populations on the electron and gas temperatures is discussed. Two electron density regimes are found, which are distinguished by the population and depopulation mechanisms for the excited states in problem. When the electron impact excitation frequency for the population or depopulation is lower than the atomic impact one, the electron density of the plasma is considered as low to estimate the population and depopulation processes. Some remarkable characteristics of population and depopulation mechanisms are found for the low electron density atmospheric plasma, where thermal relaxation by atomic collisions becomes the predominant process within the group of close-energy states in the ionizing plasma of atmospheric pressure, and the excitation temperature is almost the same as the gas temperature. In addition to the collisional relaxation by argon atoms, electron impact excitation from the ground state is also an essential population mechanism. The ratios of population density of the levels pairs, between which exists a large energy gap, include information on the electron collisional kinetics. For high electron density, the effect of atomic collisional relaxation becomes weak. For this case, the excitation mechanism is explained as electron impact ladderlike excitation similar to low-pressure ionizing plasma, since the electron collision becomes the dominant process for the population and depopulation kinetics.

  17. Work excitement in nursing: an examination of the relationship between work excitement and burnout.

    PubMed

    Sadovich, Juliana M

    2005-01-01

    The results of this study found a significant relationship between burnout and the Work Excitement Model. This suggests that utilization of the Work Excitement Model by health care organizations may reduce nursing burnout and improve productivity and quality of care. PMID:15881495

  18. On the formation of circulating patterns of excitation in anisotropic excitable media

    Microsoft Academic Search

    James P. Keener

    1988-01-01

    We present a model of excitable media with the feature that it has a vulnerable phase during which a premature current stimulus will result in the formation of a reentrant selfsustained wave of excitation. The model exploits anisotropic coupling of identical cells, and is therefore useful as a model for the myocardium. We give rigorous verification that there is a

  19. Patterns of conductivity in excitable automata with updatable intervals of excitations.

    PubMed

    Adamatzky, Andrew

    2012-11-01

    We define a cellular automaton where a resting cell excites if number of its excited neighbors belong to some specified interval and boundaries of the interval change depending on ratio of excited and refractory neighbors in the cell's neighborhood. We calculate excitability of a cell as a number of possible neighborhood configurations that excite the resting cell. We call cells with maximal values of excitability conductive. In exhaustive search of functions of excitation interval updates we select functions which lead to formation of connected configurations of conductive cells. The functions discovered are used to design conductive, wirelike, pathways in initially nonconductive arrays of cells. We demonstrate that by positioning seeds of growing conductive pathways it is possible to implement a wide range of routing operations, including reflection of wires, stopping wires, formation of conductive bridges, and generation of new wires in the result of collision. The findings presented may be applied in designing conductive circuits in excitable nonlinear media, reaction-diffusion chemical systems, neural tissue, and assemblies of conductive polymers. PMID:23214841

  20. BIOLOGICAL SCIENCES Contemporary biological science

    E-print Network

    BIOLOGICAL SCIENCES Contemporary biological science covers a range of diverse and overlapping in cellular and molecular biology. Wichita State University's Department of Biological Sciences offers courses in most aspects of contemporary biological science. Our required core courses will expose you

  1. Population of highly excited intermediate resonance states by electron transfer and excitation

    SciTech Connect

    Schuch, R. (Manne Siegbahn Institute of Physics, S-104 05 Stockholm, Sweden (SE)); Justiniano, E. (Department of Physics, East Carolina University, Greenville, North Carolina 27858-4353 (USA)); Schulz, M.; Datz, S.; Dittner, P.F.; Giese, J.P.; Krause, H.F.; Schoene, H.; Vane, R. (Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6377 (USA)); Shafroth, S. (Department of Physics, North Carolina University, Chapel Hill, North Carolina 27599-3255 (USA))

    1991-05-01

    Coincidences between two sulfur {ital K} x rays were detected from collisions of hydrogenlike S ions with H{sub 2} gas in the projectile energy range between 150 and 225 MeV. These {ital K} x rays are emitted in the decay of doubly excited states formed in the collisions via transfer and excitation. The excitation function for two coincident {ital K}{beta} transitions peaks at about 175 MeV, slightly above the expected {ital KMM} resonance energy for resonant transfer and excitation (RTE). This demonstrates the occurrence of {Delta}{ital N}{ge}2 transitions (i.e., {ital KMM} and higher resonances) in the RTE process. The cross sections for the population of the very highly excited states are higher than those predicted by theoretical calculations that use dielectronic recombination rates folded with the Compton profile for the bound electrons.

  2. Characterization of weakly excited final states by shakedown spectroscopy of laser-excited potassium

    SciTech Connect

    Schulz, J. [Department of Physical Sciences, University of Oulu, Box 3000, FIN-90014 Oulu (Finland); Department of Physics, Uppsala University, Box 530, SE-75121 Uppsala (Sweden); Heinaesmaeki, S.; Aksela, S.; Aksela, H. [Department of Physical Sciences, University of Oulu, Box 3000, FIN-90014 Oulu (Finland); Sankari, R. [Department of Physical Sciences, University of Oulu, Box 3000, FIN-90014 Oulu (Finland); Department of Physics, University of Turku, FIN-20014 Turku (Finland); Rander, T.; Lindblad, A.; Bergersen, H.; Oehrwall, G.; Svensson, S. [Department of Physics, Uppsala University, Box 530, SE-75121 Uppsala (Sweden); Kukk, E. [Department of Physics, University of Turku, FIN-20014 Turku (Finland)

    2006-07-15

    3p shakedown spectra of laser excited potassium atoms as well as direct 3p photoemission of ground state potassium have been studied. These two excitation schemes lead to the same final states and thereby provide a good basis for a detailed study of the 3p{sup 5}(4s3d){sup 1} configurations of singly ionized potassium and the photoemission processes leading to these configurations. The comparison of direct photoemission from the ground state and conjugate shakedown spectra from 4p{sub 1/2} laser excited potassium made it possible to experimentally determine the character of final states that are only weakly excited in the direct photoemission but have a much higher relative intensity in the shakedown spectrum. Based on considerations of angular momentum and parity conservation the excitation scheme of the final states can be understood.

  3. Self excitation of iron core homopolar generators

    NASA Astrophysics Data System (ADS)

    Perkins, D. E.; Nalty, K. E.; Walls, W. A.

    1986-11-01

    In the interest of reducing homopolar generator (HPG) auxiliary requirements, a self-excited field coil for pulsed duty, iron-core HPG has been developed and tested at the Center for Electromechanics at the University of Texas. In order to minimize rotor energy expended during excitation, a low-resistance, low-inductance coil was desired to allow field current to rise as rapidly as possible. A seven-turn field coil, having a nominal resistance of 500 micro-ohms was fabricated for the compact HPG system tester and subsequently tested. At 6,000 rpm, a field current rise time of 1 sec was achieved and resulted in an average peak field density of 1.94 T. Only 300 kJ, about 13 percent of the 2.27 MJ stored in the rotor was required to fully excite the generator.

  4. Artificial Excitation of Schumann Resonance with HAARP

    NASA Astrophysics Data System (ADS)

    Streltsov, A. V.; Chang, C. L.

    2014-12-01

    We report results from the experiment aimed at the artificial excitation of extremely-low-frequency (ELF) electromagnetic waves with frequencies corresponding to the frequency of Schumann resonance (typically, 7.5 - 8.0 Hz frequency range). Electromagnetic waves with these frequencies can form a standing pattern inside the spherical cavity formed by the surface of the earth and the ionosphere. In the experiment the ELF waves were excited by heating the ionosphere with X-mode HF electromagnetic waves generated by the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. The experiment demonstrates that heating of the ionosphere can excite relatively large-amplitude electromagnetic waves with frequencies in the range of the Schumann resonance, when the ionosphere has a strong F-layer and an electric field greater than 5 mV/m is present in the E-region.

  5. Experimental uncertainty associated with traveling wave excitation

    NASA Astrophysics Data System (ADS)

    Cox, Geofrey S.

    This dissertation research produces the experimental techniques required to evaluate mistuning in any rotor. Within operation, a rotor is subjected to a unique pattern of frequencies acting to excite the rotor. Utilizing traveling wave excitation, a rotor's critical frequencies and the respective excitation pattern are reproduced. Individual rotor blade frequency response functions are evaluated and statistically analyzed. The experimental results serve to not only verify the degree to which a rotor is mistuned, but also to provide an indication of the forced response amplification the mistuning induces. Within the experiment, definitive specifications were developed to ensure peak rotor responses. Numerical simulations of the experiment were performed in ANSYS using a model developed by way of structured light scanning. With experimental and numerical eigenvalue differences of less than 1%, the unique modeling technique, capturing a rotor's geometric mistuning, is a valid method to predict a rotor's natural frequencies. Furthermore these same numerical results serve to validate the experimental free boundary assumption.

  6. Nanoscale control of phonon excitations in graphene

    PubMed Central

    Kim, Hyo Won; Ko, Wonhee; Ku, JiYeon; Jeon, Insu; Kim, Donggyu; Kwon, Hyeokshin; Oh, Youngtek; Ryu, Seunghwa; Kuk, Young; Hwang, Sung Woo; Suh, Hwansoo

    2015-01-01

    Phonons, which are collective excitations in a lattice of atoms or molecules, play a major role in determining various physical properties of condensed matter, such as thermal and electrical conductivities. In particular, phonons in graphene interact strongly with electrons; however, unlike in usual metals, these interactions between phonons and massless Dirac fermions appear to mirror the rather complicated physics of those between light and relativistic electrons. Therefore, a fundamental understanding of the underlying physics through systematic studies of phonon interactions and excitations in graphene is crucial for realising graphene-based devices. In this study, we demonstrate that the local phonon properties of graphene can be controlled at the nanoscale by tuning the interaction strength between graphene and an underlying Pt substrate. Using scanning probe methods, we determine that the reduced interaction due to embedded Ar atoms facilitates electron–phonon excitations, further influencing phonon-assisted inelastic electron tunnelling. PMID:26109454

  7. Shear layer excitation, experiment versus theory

    NASA Technical Reports Server (NTRS)

    Bechert, D. W.; Stahl, B.

    1984-01-01

    The acoustical excitation of shear layers is investigated. Acoustical excitation causes the so-called orderly structures in shear layers and jets. Also, the deviations in the spreading rate between different shear layer experiments are due to the same excitation mechanism. Measurements in the linear interaction region close to the edge from which the shear layer is shed are examined. Two sets of experiments (Houston 1981 and Berlin 1983/84) are discussed. The measurements were carried out with shear layers in air using hot wire anemometers and microphones. The agreement between these measurements and the theory is good. Even details of the fluctuating flow field correspond to theoretical predictions, such as the local occurrence of negative phase speeds.

  8. Testing the excitability of human motoneurons

    PubMed Central

    McNeil, Chris J.; Butler, Jane E.; Taylor, Janet L.; Gandevia, Simon C.

    2013-01-01

    The responsiveness of the human central nervous system can change profoundly with exercise, injury, disuse, or disease. Changes occur at both cortical and spinal levels but in most cases excitability of the motoneuron pool must be assessed to localize accurately the site of adaptation. Hence, it is critical to understand, and employ correctly, the methods to test motoneuron excitability in humans. Several techniques exist and each has its advantages and disadvantages. This review examines the most common techniques that use evoked compound muscle action potentials to test the excitability of the motoneuron pool and describes the merits and limitations of each. The techniques discussed are the H-reflex, F-wave, tendon jerk, V-wave, cervicomedullary motor evoked potential (CMEP), and motor evoked potential (MEP). A number of limitations with these techniques are presented. PMID:23630483

  9. Resonance Raman excitation profiles of lycopene

    NASA Astrophysics Data System (ADS)

    Hoskins, L. C.

    1981-01-01

    The resonance Raman spectrum of lycopene has been examined in acetone solvent and excitation profiles of the three fundamentals ?1, ?2, and ?3 have been determined. The excitation data and the visible spectrum have been analyzed using two-mode and three-mode vibrational models, with the two-mode model involving virtual states of ?1 and ?2 giving the best fit to the data. This mode mixing or Duskinsky effect was not observed for ?-carotene. The single-mode and three-mode theories which have been used to explain the corresponding data for ?-carotene are shown to be inconsistent with the experimental data of lycopene. Equations for calculating excitation profiles and visible spectra are given.

  10. Nanoscale control of phonon excitations in graphene.

    PubMed

    Kim, Hyo Won; Ko, Wonhee; Ku, JiYeon; Jeon, Insu; Kim, Donggyu; Kwon, Hyeokshin; Oh, Youngtek; Ryu, Seunghwa; Kuk, Young; Hwang, Sung Woo; Suh, Hwansoo

    2015-01-01

    Phonons, which are collective excitations in a lattice of atoms or molecules, play a major role in determining various physical properties of condensed matter, such as thermal and electrical conductivities. In particular, phonons in graphene interact strongly with electrons; however, unlike in usual metals, these interactions between phonons and massless Dirac fermions appear to mirror the rather complicated physics of those between light and relativistic electrons. Therefore, a fundamental understanding of the underlying physics through systematic studies of phonon interactions and excitations in graphene is crucial for realising graphene-based devices. In this study, we demonstrate that the local phonon properties of graphene can be controlled at the nanoscale by tuning the interaction strength between graphene and an underlying Pt substrate. Using scanning probe methods, we determine that the reduced interaction due to embedded Ar atoms facilitates electron-phonon excitations, further influencing phonon-assisted inelastic electron tunnelling. PMID:26109454

  11. Electron-impact vibrational excitation of cyclopropane.

    PubMed

    ?urík, R; ?ársky, P; Allan, M

    2015-04-14

    We report a very detailed test of the ab initio discrete momentum representation (DMR) method of calculating vibrational excitation of polyatomic molecules by electron impact, by comparison of its results with an extensive set of experimental data, covering the entire range of scattering angles from 10° to 180° and electron energies from 0.4 to 20 eV. The DMR calculations were carried out by solving the two-channel Lippmann-Schwinger equation in the momentum space, and the interaction between the scattered electron and the target molecule was described by exact static-exchange potential corrected by a density functional theory (DFT) correlation-polarization interaction that models target's response to the field of incoming electron. The theory is found to quantitatively reproduce the measured spectra for all normal modes, even at the difficult conditions of extreme angles and at low energies, and thus provides full understanding of the excitation mechanism. It is shown that the overlap of individual vibrational bands caused by limited experimental resolution and rotational excitation must be properly taken into account for correct comparison of experiment and theory. By doing so, an apparent discrepancy between published experimental data could be reconciled. A substantial cross section is found for excitation of the non-symmetric HCH twisting mode ?4 of A1 (?) symmetry by the 5.5 eV A2 (') resonance, surprisingly because the currently accepted selection rules predict this process to be forbidden. The DMR theory shows that the excitation is caused by an incoming electron in an f-wave of A2 (') symmetry which causes excitation of the non-symmetric HCH twisting mode ?4 of the A1 (?) symmetry and departs in p- and f-waves of A2 (?) symmetry. PMID:25877583

  12. Excitation of Lunar Eccentricity by Planetary Resonances

    NASA Astrophysics Data System (ADS)

    Cuk, Matija

    2007-07-01

    The present free eccentricity (e) of the Moon's orbit is 0.052, and direct measurements using lunar laser-ranging (Williams et al. 2001) have shown it to be currently slowly increasing due to dominance of Earth's ocean tides over lunar satellite tides. Since the tidal e-excitation is just a side effect of orbital expansion, its significance for lunar e must have been greatest during the Hadean eon (4.5-4 Gyr ago). Therefore, tidal excitation is unlikely to have produced the present e of the Moon, as the efficiency of ocean tides must have been much lower in the distant past (Bills and Ray 1999 and references therein), and the Moon's e was likely damped, rather than excited, at this epoch. Kaula and Yoder (1976) proposed that lunar e might have been excited by a temporary capture in the Jovian evection resonance (at 53 R_E, when the lunar apsidal precession period equaled one Jovian year). We perfomed numerical integrations of that resonance passage, and found that the secular variations of Earth's orbit make capture impossible, but lead to hundreds of resonance passages as the resonance slightly shifts its location. These passages lead to a "random-walk" type changes in lunar eccentricity. If the pre-resonance eccentricity of the Moon was 0.005-0.01, the average post-resonance one is about 0.03-0.04 (with the tidal excitation subsequently bringing e up to its present level). We also discovered another planetary resonance of similar strength at about 46 R_E, involving the 1:2 commensurability with the 8-year 3:5 inequality between Earth and Venus. This resonance is strong enough to enhance small lunar eccentricities by a factor of few. A pre-resonance free e of 0.001 can plausibly be a product of tidal excitation, allowing for a total circularization of lunar orbit at some point in the past.

  13. BROADBAND EXCITATION IN NUCLEAR MAGNETIC RESONANCE

    SciTech Connect

    Tycko, R.

    1984-10-01

    Theoretical methods for designing sequences of radio frequency (rf) radiation pulses for broadband excitation of spin systems in nuclear magnetic resonance (NMR) are described. The sequences excite spins uniformly over large ranges of resonant frequencies arising from static magnetic field inhomogeneity, chemical shift differences, or spin couplings, or over large ranges of rf field amplitudes. Specific sequences for creating a population inversion or transverse magnetization are derived and demonstrated experimentally in liquid and solid state NMR. One approach to broadband excitation is based on principles of coherent averaging theory. A general formalism for deriving pulse sequences is given, along with computational methods for specific cases. This approach leads to sequences that produce strictly constant transformations of a spin system. The importance of this feature in NMR applications is discussed. A second approach to broadband excitation makes use of iterative schemes, i.e. sets of operations that are applied repetitively to a given initial pulse sequences, generating a series of increasingly complex sequences with increasingly desirable properties. A general mathematical framework for analyzing iterative schemes is developed. An iterative scheme is treated as a function that acts on a space of operators corresponding to the transformations produced by all possible pulse sequences. The fixed points of the function and the stability of the fixed points are shown to determine the essential behavior of the scheme. Iterative schemes for broadband population inversion are treated in detail. Algebraic and numerical methods for performing the mathematical analysis are presented. Two additional topics are treated. The first is the construction of sequences for uniform excitation of double-quantum coherence and for uniform polarization transfer over a range of spin couplings. Double-quantum excitation sequences are demonstrated in a liquid crystal system. The second additional topic is the construction of iterative schemes for narrowband population inversion. The use of sequences that invert spin populations only over a narrow range of rf field amplitudes to spatially localize NMR signals in an rf field gradient is discussed.

  14. LMM Auger primary excitation spectra of copper

    NASA Astrophysics Data System (ADS)

    Pauly, N.; Tougaard, S.; Yubero, F.

    2014-12-01

    The shape and intensity of measured Auger peaks are strongly affected by extrinsic excitations due to electron transport out of the surface and to intrinsic excitations induced by the sudden creation of the two static core holes. Following a method developed for XPS in a previous work [N. Pauly, S. Tougaard, F. Yubero, Surf. Sci. 620 (2014) 17], we have calculated the effective energy-differential inelastic electron scattering cross-sections, including the effects of the surface and of the two core holes, within the dielectric response theory by means of the QUEELS-XPS software (QUantitative analysis of Electron Energy Losses at Surfaces for XPS). The Auger spectra are then modeled by convoluting this energy loss cross section with the primary excitation spectrum that accounts for all effects which are part of the initial Auger process, i.e. L-S coupling and vacancy satellite effects. The shape of this primary excitation spectrum is fitted to get close agreement between the theoretical and the experimental spectra obtained from X-ray excited Auger electron spectroscopy (XAES). We have performed these calculations of XAES spectra for various LMM Auger transitions of pure Cu (L3M45M45, L3M23M45, L3M23M23 and L2M45M45 transitions). We compare the resulting primary excitation spectra with theoretical results published in the literature and obtain reasonable quantitative agreement. In particular, we extract from experimental spectra quantitative intensities due to Coster-Kronig, shake-off and shake-up processes relative to the intensity from the “normal” Auger process.

  15. Study of excited levels in 147Pm

    NASA Astrophysics Data System (ADS)

    Urban, W.; Durell, J. L.; Phillips, W. R.; Varley, B. J.; Hess, Ch. P.; Jones, M. A.; Pearson, C. J.; Vermeer, W. J.; Vieu, Ch.; Dionisio, J. S.; Pautrat, M.; Bacelar, J. C.

    1995-02-01

    Excited states in 147Pm have been studied through the 136Xe( 15N,4n) and 148Nd(d,3n) compound nucleus reactions. A solid xenon target has been used to populate high-spin states in 147Pm. Conversion coefficients of weak transitions were determined measuring electron-? coincidences. The half-life of the isomeric level at 649.3 keV has been remeasured to be 27 ± 3 ns. An extended level scheme is proposed, which is discussed in terms of single-particle excitations and collective quadrupole and octupole vibrations coupled to them. The possible presence of octupole deformation is considered.

  16. Formalism of collective electron excitations in fullerenes

    NASA Astrophysics Data System (ADS)

    Verkhovtsev, A.; Korol, A. V.; Solov'yov, A. V.

    2012-10-01

    A formalism for the description of collective electron excitations in fullerenes by inelastic scattering of fast electrons within the plasmon resonance approximation is presented. Considering the system as a spherical shell of a finite width, we show that the differential cross section is defined by three plasmon excitations, namely two coupled modes of the surface plasmon and the volume plasmon. The interplay of the three plasmons appears due to the electron diffraction of the fullerene shell. Plasmon modes of different angular momenta provide dominating contributions to the differential cross section depending on the transferred momentum.

  17. Mexican waves in an excitable medium.

    PubMed

    Farkas, I; Helbing, D; Vicsek, T

    2002-09-12

    The Mexican wave, or La Ola, which rose to fame during the 1986 World Cup in Mexico, surges through the rows of spectators in a stadium as those in one section leap to their feet with their arms up, and then sit down again as the next section rises to repeat the motion. To interpret and quantify this collective human behaviour, we have used a variant of models that were originally developed to describe excitable media such as cardiac tissue. Modelling the reaction of the crowd to attempts to trigger the wave reveals how this phenomenon is stimulated, and may prove useful in controlling events that involve groups of excited people. PMID:12226653

  18. Double Photoionization of excited Lithium and Beryllium

    SciTech Connect

    Yip, Frank L.; McCurdy, C. William; Rescigno, Thomas N.

    2010-05-20

    We present total, energy-sharing and triple differential cross sections for one-photon, double ionization of lithium and beryllium starting from aligned, excited P states. We employ a recently developed hybrid atomic orbital/ numerical grid method based on the finite-element discrete-variable representation and exterior complex scaling. Comparisons with calculated results for the ground-state atoms, as well as analogous results for ground-state and excited helium, serve to highlight important selection rules and show some interesting effects that relate to differences between inter- and intra-shell electron correlation.

  19. Collective charge excitations along cell membranes

    E-print Network

    Efstratios Manousakis

    2004-11-18

    A significant part of the thin layers of counter-ions adjacent to the exterior and interior surfaces of a cell membrane form quasi-two-dimensional (2D) layers of mobile charge. Collective charge density oscillations, known as plasmon modes, in these 2D charged systems of counter-ions are predicted in the present paper. This is based on a calculation of the self-consistent response of this system to a fast electric field fluctuation. The possibility that the membrane channels might be using these excitations to carry out fast communication is suggested and experiments are proposed to reveal the existence of such excitations.

  20. From Fusion Hierarchy to Excited State TBA

    E-print Network

    G. Juettner; A. Kluemper; J. Suzuki

    1997-07-08

    Functional relations among the fusion hierarchy of quantum transfer matrices give a novel derivation of the TBA equations, namely without string hypothesis. This is demonstrated for two important models of 1D highly correlated electron systems, the supersymmetric $t-J$ model and the supersymmetric extended Hubbard model. As a consequence, "the excited state TBA" equations, which characterize correlation lengths, are explicitly derived for the $t-J$ model. To the authors' knowledge, this is the first explicit derivation of excited state TBA equations for 1D lattice electron systems.

  1. Gluonic excitations in the hadronic spectrum

    SciTech Connect

    Dudek, Jozef J. [ODU, JLAB

    2014-06-01

    QCD at low energy features a gluonic field that is strongly coupled to itself and to quarks. I will present a summary of what we know about the role that excitations of the gluonic field play in determining the spectrum of meson resonances. Recent studies using lattice techniques have suggested a phenomenology of gluonic excitations within QCD that leads to hybrid mesons with both exotic and non-exotic quantum numbers. I will discuss these calculations and describe their relationship to current experimental knowledge and to forthcoming experiments at Jefferson Lab and elsewhere.

  2. Stability of excited bosonic stellar configurations

    NASA Astrophysics Data System (ADS)

    Jetzer, Ph.

    1989-05-01

    In this paper I study the problem of the dynamical stability of Bose star configurations which correspond to excited states. In particular I show that the eigenvalues of the pulsation equation, which governs the time evolution of the infinitesimal radial oscillations, are real. This, together with the theorem, proved by Lee and Pang, that for a configuration with critical central density ?crit the pulsation equation has a zero mode and the fact that for central densities much smaller than ?crit the lowest eigenvalue is positive, leads to the conclusion that the excited Bose star configurations are classically stable for central densities up to ?crit.

  3. Relativistic Coulomb excitation at small impact parameters

    E-print Network

    B. F. Bayman; F. Zardi

    2006-05-22

    The semiclassical model of relativistic Coulomb excitation is studied in situations in which the impact parameter is small enough so that projectile and target charge distributions overlap. The electromagnetic effects of this overlap are shown to be small. Realistic nucleon-nucleon reaction cross-sections, and realistic nuclear radial charge and matter distributions are used to determine a formula for the lower impact parameter limit to be used in the calculation of the Coulomb excitation cross-section. A wide selection of projectile-target pairs is explored, in the bombarding energy range of 1 GeV to 5 GeV per nucleon.

  4. Photoassociation in cold atoms via ladder excitation.

    PubMed

    Trachy, M L; Veshapidze, G; Shah, M H; Jang, H U; DePaola, B D

    2007-07-27

    We explore 2-color photoassociative ionization in cold Rb vapor and present experimental evidence that the molecular ions are produced from the stepwise excitation of a ladder of molecular states. We also explore a new process, dubbed photoassociative-dissociative ionization, by which atomic ions are created by excitation through a ladder of molecular states, finally autoionizing to a dissociative potential curve of Rb2+. We submit that these experiments could be the starting point for the same sort of high resolution spectroscopy that has already been done for lower electronic states of cold Rb2 at large internuclear separation. PMID:17678360

  5. Selective excitation of two-dimensional arbitrarily shaped voxels with parallel excitation in spectroscopy.

    PubMed

    Snyder, Jeff; Haas, Martin; Hennig, Jürgen; Zaitsev, Maxim

    2012-02-01

    Parallel excitation is being studied intensively for applications in MR imaging and in particular for selecting arbitrary shapes as regions of interest. In this work, parallel excitation was applied to arbitrarily shaped voxel selection in spectroscopy and investigated for different excitation k-space trajectories (radial, rectilinear, and spiral) and acceleration factors. Each trajectory was segmented into multiple excitations to increase the overall bandwidth during target selection. Acceleration by parallel excitation was used to decrease the number of segments. Evaluation of spatial and spectral localization of the target of interest was performed in simulation and phantom experiments, and was compared with the point resolved spectroscopy (PRESS) experiment with standard voxels. The selective excitation experiments demonstrated excellent spatial localization and a broad frequency response, although PRESS was superior in direct comparisons with respect to signal-to-noise ratio (SNR) and outer volume suppression. Extensive SNR variation was observed dependent on trajectory (8%-90%), with the preferred radial case producing approximately 40%-60% SNR of the PRESS case. Accelerated trajectories at R = 4 provided comparable artifact signal and target excitation accuracy compared with their nonaccelerated counterparts; however, further acceleration (R = 8) resulted in increased artifact (33% increase at R = 8). PMID:21721040

  6. Quasiparticle theory of electron excitations in solids

    SciTech Connect

    Louie, S.G.

    1995-10-01

    A first-principles quasiparticle approach to electron excitation energies in solids is reviewed. The theory has been applied to explain and predict the spectroscopic properties of a variety of systems including bulk crystals, surfaces, interfaces, clusters, defects, and materials under pressure. Several illustrative applications are presented and some recent theoretical developments discussed.

  7. New Logic Circuit with DC Parametric Excitation

    NASA Astrophysics Data System (ADS)

    Sugahara, Masanori; Kaneda, Hisayoshi

    1982-12-01

    It is shown that dc parametric excitation is possible in a circuit named JUDO, which is composed of two resistively-connected Josephson junctions. Simulation study proves that the circuit has large gain and properties suitable for the construction of small, high-speed logic circuits.

  8. Injection locking conditions under small periodic excitations

    Microsoft Academic Search

    Mark M. Gourary; Sergey G. Rusakov; Sergey L. Ulyanov; Michael M. Zharov; Brian J. Mulvaney; Kiran K. Gullapalli

    2008-01-01

    Injection locking of oscillators subject to small periodic excitations is derived from existence conditions of the solution of the small signal harmonic balance degenerate system. The resulting expression for the locking range can be applied to any oscillator circuit with arbitrary periodic injection waveform, and can be easily implemented into a circuit simulator. The application of the general expression to

  9. Hexadecapolar excitation in sup 100 Ru

    SciTech Connect

    Sirota, S.; Duarte, J.L.M.; Horodynski-Matsushigue, L.B.; Borello-Lewin, T. (Instituto de Fisica da Universidade de Sa Paulo, 01498 Sao Paulo, Brasil (BR))

    1989-09-01

    Attention is drawn to the strong collective {ital L}=4 direct excitation of the state at 2.367 MeV in {sup 100}Ru by inelastic scattering of 16 MeV protons characterized by a deformation parameter {beta}{sub 4}=0.10, one of the highest reported for any region of the mass table.

  10. Magnetic performance of a fast excitation wiggler

    SciTech Connect

    Gallardo, J.C.; Romano, T.; van Steenbergen, A.

    1993-03-01

    With the objective of performing an inverse free-electron laser accelerator experiment, an iron dominated (Vanadium Permendur), fast excitation, high K planar wiggler has been built and measured. The authors present in this report an analysis of a constant period wiggler and several tapering configurations (gap=4 mm; 3.0 cm < [lambda][sub [omega

  11. Nonmonotonic excitation rates in argon positive column

    SciTech Connect

    Arslanbekov, R.R.; Kolobov, V.I.; Bogdanov, E.A.; Kudryavtsev, A.A. [CFD Research Corporation, Huntsville, Alabama, 35805 (United States); St. Petersburg State University, 198504 (Russian Federation)

    2004-10-18

    Nonmonotonic radial distributions of electron excitation rates are obtained in simulations of positive column (PC) in argon for a wide range of gas pressures 5

  12. The CLAS Excited Baryon Program at Jlab

    SciTech Connect

    Volker Crede

    2007-10-01

    Nucleons are complex systems of confined quarks and exhibit characteristic spectra of excited states. Highly excited nucleon states are sensitive to details of quark confinement which is poorly understood within Quantum Chromodynamics (QCD), the fundamental theory of strong interactions. Thus, measurements of excited states and the corresponding determination of their properties are needed to come to a better understanding of how confinement works in nucleons. However, the excited states of the nucleon cannot simply be inferred from cleanly separated spectral lines. Quite the contrary, a spectral analysis in nucleon resonance physics is challenging because of the fact that the resonances are broadly overlapping states which decay into a multitude of final states involving mesons and baryons. To provide a consistent and complete picture of an individual nucleon resonance, the various possible production and decay channels must be treated in a multichannel framework that permits separating resonance from background contributions. Very often, resonances reveal themselves more clearly through interference with dominant amplitudes. These interference terms can be isolated via polarization observables. The current CLAS effort is to utilize highly-polarized hydrogen and deuterium targets as well as polarized photon beams toward a complete measurement of a large number of reaction channels.

  13. The CLAS Excited Baryon Program at JLab

    SciTech Connect

    Crede, Volker [Florida State University, Tallahassee, FL 32306 (United States)

    2007-10-26

    Nucleons are complex systems of confined quarks and exhibit characteristic spectra of excited states. Highly excited nucleon states are sensitive to details of quark confinement which is poorly understood within Quantum Chromodynamics (QCD), the fundamental theory of strong interactions. Thus, measurements of excited states and the corresponding determination of their properties are needed to come to a better understanding of how confinement works in nucleons. However, the excited states of the nucleon cannot simply be inferred from cleanly separated spectral lines. Quite the contrary, a spectral analysis in nucleon resonance physics is challenging because of the fact that the resonances are broadly overlapping states which decay into a multitude of final states involving mesons and baryons. To provide a consistent and complete picture of an individual nucleon resonance, the various possible production and decay channels must be treated in a multichannel framework that permits separating resonance from background contributions. Very often, resonances reveal themselves more clearly through interference with dominant amplitudes. These interference terms can be isolated via polarization observables. The current CLAS effort is to utilize highly-polarized hydrogen and deuterium targets as well as polarized photon beams toward a complete measurement of a large number of reaction channels.

  14. Collective excitations in neutron-star crusts

    E-print Network

    N. Chamel; D. Page; S. Reddy

    2013-10-15

    We explore the spectrum of low-energy collective excitations in the crust of a neutron star, especially in the inner region where neutron-proton clusters are immersed in a sea of superfluid neutrons. The speeds of the different modes are calculated systematically from the nuclear energy density functional theory using a Skyrme functional fitted to essentially all experimental atomic mass data.

  15. Excitation of XUV radiation in solar flares

    NASA Technical Reports Server (NTRS)

    Emslie, A. Gordon

    1992-01-01

    The goal of the proposed research was to understand the means by which XUV radiation in solar flares is excited, and to use this radiation as diagnostics of the energy release and transport processes occurring in the flare. Significant progress in both of these areas, as described, was made.

  16. From fusion hierarchy to excited state TBA

    Microsoft Academic Search

    G. Jüttner; A. Klümper; J. Suzuki

    1998-01-01

    Functional relations among the fusion hierarchy of quantum transfer matrices give a novel derivation of the TBA equations, namely without string hypothesis. This is demonstrated for two important models of 1D highly correlated electron systems, the supersymmetric t-J model and the supersymmetric extended Hubbard model. As a consequence, “the excited state TBA” equations, which characterize correlation lengths, are explicitly derived

  17. Optical excitation of surface plasmons: An introduction

    Microsoft Academic Search

    J. R. Sambles; G. W. Bradbery; Fuzi Yang

    1991-01-01

    Beginning from low level concepts the basic understanding for the optical excitation of surface plasmons is developed. Prism coupling using the attenuated total reflection technique is discussed as well as the less traditional grating coupling technique. A brief discussion of some recent developments using twisted gratings is also presented. Finally a short summary of the potential device applications is given.

  18. Photon Excitation of Sodium Emission in Comets

    Microsoft Academic Search

    E. A. Baranovsky; V. P. Tarashchuk

    2004-01-01

    We consider the possibility of the excitation of sodium resonance emission in cometary matter under solar radiation at a heliocentric distance of 5 AU, as was observed when a fragment of Comet Shoemaker-Levy 9 plunged into Jupiter. When the sodium emission is calculated, the multiple scattering in the cometary cloud is taken into account. We use a non-LTE radiative transfer

  19. The Interactions and Excitations of Gauge Vortices

    Microsoft Academic Search

    Mark Gower Alford

    1990-01-01

    Gauge vortices, for example cosmic strings, are topological solitons produced in the spontaneous breakdown of gauge symmetries, and possess long range pure gauge fields associated with the broken symmetries. This thesis explores the interactions of matter with the gauge field of a vortex, and the low energy excitations (zero modes) of the vortex. The interactions occur via the Aharonov -Bohm

  20. Engage and Excite Students with Educational Games

    ERIC Educational Resources Information Center

    Petsche, Jennifer

    2011-01-01

    Using educational games to learn or reinforce lessons engages students and turns a potentially boring subject into something exciting and desirable to know! Games offer teachers and parents a new way to grab students' attention so that they will retain information. Games have become a teaching tool, an invaluable resource for reaching students in…

  1. Nuclear Excitation by Electronic Transition - NEET

    SciTech Connect

    Becker, J.A.

    2002-06-10

    Experiments seeking to demonstrate nuclear excitation induced by synchrotron radiation have been enabled by the development of intense synchrotron radiation. The phenomena has been demonstrated in {sup 197}Au, while realistic upper limits for {sup 189}Os have been established. A new experiment in {sup 189}Os is described. The experimental claim of NEET in isomeric {sup 178}Hf is not credible.

  2. IC-excited strontium recombination laser

    Microsoft Academic Search

    N. K. Vuchkov; D. N. Astadjov

    1995-01-01

    An IC-excited Sr+ recombination laser, operated successfully at average powers of 0.8 W-1 W, is reported. The IC-circuitry practically eliminates the detrimental ringing of the tube current and ensures tripling (or more) of the rectifier voltage to be imposed on the tube electrodes.

  3. Magnetic Field Mapping by Selective Equipotential Excitation

    Microsoft Academic Search

    Ouajdi Felfoul; Michelle Raimbert; Sylvain Martel

    2006-01-01

    A new magnetic field mapping method in MRI is presented. This technique is ideal for severe inhomogeneities where plane warp cannot be ignored. The present study employs a ferromagnetic ball to create a perturbation within the imaged volume. The magnetic moment and position of the device are acquired experimentally with a new technique that excites magnetic equipotentials within a volume.

  4. Noise spectrum of pulse excited fluxgate sensor

    Microsoft Academic Search

    Jan Kubik; Pavel Ripka

    2006-01-01

    A low-cost flat miniature fluxgate magnetic field sensor is excited by short current pulses in order to reduce the power consumption. In this mode, the output signal contains very rich spectrum of even harmonics, each of them being sensitive to the measured field. The noise spectrum of individual harmonics, both in the untuned and tuned modes, was measured. The output

  5. Parametric Excitation Mechanisms for Dynamic Bipedal Walking

    Microsoft Academic Search

    Fumihiko Asano; Sang-ho Hyon; Zhi Wei Luo

    2005-01-01

    It is already clarified throughout studies of passive dynamic walking mechanisms that the common nec essary condition for dynamic gait generation comes from the requirement on mechanical energy restoration. Until now we have treated only rotational joints of the robot, whereas in this paper we consider a novel dynamic gait generation method based on mechanical energy restoration by parametric excitation

  6. Robust decentralized exciter control with linear feedback

    Microsoft Academic Search

    Aleksandar I. Zecevic; Gordana Neskovic; Dragoslav D. Siljak

    2004-01-01

    A new strategy is developed for the design of robust decentralized exciter control in power systems. The method is computationally attractive and the resulting feedback is linear, which allows for easy implementation. Experiments on the IEEE 39 bus system demonstrate that such a control is robust with respect to the fault location and to variations in the system operating point.

  7. Exploring Excited Hadrons in Lattice QCD

    E-print Network

    Colin Morningstar; for the Hadron Spectrum Collaboration

    2009-05-27

    Progress in extracting the spectrum of excited hadron resonances in lattice QCD Monte Carlo calculations is reviewed and the key issues and challenges in such computations are outlined. The importance of multi-hadron states as simulations with lighter pion masses are done is discussed, and the need for all-to-all quark propagators is emphasized.

  8. Lessons Learned from Conducting a K-12 Project to Revitalize Achievement by Using Instrumentation in Science Education

    ERIC Educational Resources Information Center

    Kapila, Vikram; Iskander, Magued

    2014-01-01

    A student's first introduction to engineering and technology is typically through high school science labs. Unfortunately, in many high schools, science labs often make use of antiquated tools that fail to deliver exciting lab content. As a result, many students are turned off by science, fail to excel on standardized science exams, and do…

  9. Science history

    Microsoft Academic Search

    A J Woodall

    1967-01-01

    A science history content in a science course is a humanizing element which makes the science appeal more strongly to imaginative and creative minds. It also provides perspective and prepares the pupil for the ever-changing character of modern science. Examples are given of charts which can key science history to its social and political background and which illustrate the interdependence

  10. MarsQuest: Bringing the Excitement of Mars Exploration to the Public

    NASA Astrophysics Data System (ADS)

    Dusenbery, P. B.; Morrow, C. A.; Harold, J. B.

    2005-08-01

    We are in the midst of an extraordinary era of Mars exploration with missions like NASA's Odyssey and Mars Global Surveyor and ESA's Mars Express spacecraft along with NASA's Mars Exploration Rovers returning results that expand our knowledge and understanding of the Red Planet. To bring the excitement of Mars exploration to the public, the Space Science Institute (SSI) of Boulder, CO, has developed a comprehensive Mars Education Program that includes: 1) large and small traveling exhibits, 2) workshops for educators and docents, and 3) an interactive Web site called MarsQuest Online (in partnership with TERC and JPL). This program will be presented and offered as a good model for actively involving scientists and their discoveries to improve science education. The centerpiece of SSI's Mars Education Program is the 5,000-square-foot traveling exhibition, MarsQuest: Exploring the Red Planet, which was developed with support from the National Science Foundation (NSF), NASA, and several corporate donors. The MarsQuest exhibit is on a six-year tour that began in 1998. The exhibit is currently at the Life Science Centre, Newcastle upon Tyne, UK. The Institute has also developed Destination: Mars, a mini-version of MarsQuest that is designed for smaller venues. Workshops for educators and docents are conducted at host sites. They are designed to inspire and empower participants to extend the excitement and science content of the exhibitions to students and museum visitors. MarsQuest Online is a Web site that uses the MarsQuest exhibit as a framework for online interactives that delve deeper into Mars science. The Mars Education Program also provides a context for educational research on effective educational programming and web-based versus exhibit delivery of interactives. The results of this research inform subsequent exhibit projects, (e.g. Giant Planets) and are disseminated to the broader informal science community.

  11. Continuous Microwave Excitation of Excimer Lamps.

    NASA Astrophysics Data System (ADS)

    Hassal, Scott Bradley

    1991-01-01

    For decades, microwaves have been used to create gas discharges for many applications. This thesis deals with the use of microwaves to excite gas discharges for incoherent optical sources, with particular emphasis on excimer systems. In addition, microwave excitation of a gas laser is considered. A novel apparatus was designed and built to couple 2.45-GHz microwave radiation into a gas discharge. The microwave resonator is the essential part of this equipment, and a detailed discussion of its design and performance is given. The resonator is characterized both theoretically and experimentally in order to determine the coupling efficiency and peak electric-field strength. Specialized theory is developed in order to evaluate many parameters of a microwave-excited discharge. The phenomenon of skin effect is investigated quantitatively and expressions for the plasma frequency and electron density are developed in terms of collision frequency and observable parameters (e.g., skin depth). Expressions for peak electric-field strength, ionization coefficient and collisionless electron energy are also developed. The results of an extensive investigation of continuous-wave microwave-excited excimer fluorescence are reported. Rare-gas halide, homonuclear halogen and heteronuclear halogen systems are examined and the corresponding ultraviolet spectra are presented. Truly continuous excimer emission has been achieved (for the first time) on several transitions. For systems of particular interest (e.g. XeCl and KrCl), the effects of total pressures and gas composition on fluorescence output are investigated, and the appropriate spectra are presented. Finally, the potential operation of microwave-excited carbon dioxide and argon-ion gas lasers is investigated, and upper limits are deduced for the small-signal gain under various conditions.

  12. Coherent Atomic Excitation in AN Optical Cavity.

    NASA Astrophysics Data System (ADS)

    Shaw, Michael James

    This dissertation presents a procedure for treating coherent excitation of an atomic vapor in a radiation-filled cavity. Specifically, it describes a technique for solving the coupled Maxwell-Bloch equations for moving two-state atoms in a one dimensional cavity by means of a spatial quasi-Fourier expansion that introduces spatial harmonics for the atomic populations and the coherence. To utilize this technique, I have developed a computer code, CAVITY, which solves the resulting coupled differential equations for the evolution on the spatial coefficients accurately and efficiently. This dissertation is divided into two parts. The first part describes the physical and numerical models used in CAVITY. The second section of the dissertation presents numerical simulations performed by the code. This section begins with a thorough analysis of atoms in the zero-density limit interacting with a standing wave field. This analysis is then extended into the high density regime with an examination of the excitation and ionization of two-level homogeneously and inhomogeneously broadened atoms in a high-Q cavity standing wave field. This section continues with a presentation the analysis of collisions of counterpropagating optical solitons. I complete this section with an examination of the temporal compression of intense unidirectional optical pulses using frequency modulation and the dispersion of near-resonant atomic vapor. The simulations of bidirectional excitation present new and important phenomena arising from the proper treatment of coherent excitation by interfering fields. These effects have been approximated with truncated series expansions or ignored in previous work. In addition, both the bidirectional and unidirectional simulations illustrate that the numerical methods used in the code lead to an efficient and accurate solution of the equations of motion. The simulations also show that the code is capable of treating a wide variety of excitation phenomena.

  13. Cascadable excitability in optically injected microdisks

    NASA Astrophysics Data System (ADS)

    Van Vaerenbergh, Thomas; Alexander, Koen; Fiers, Martin; Mechet, Pauline; Dambre, Joni; Bienstman, Peter

    2014-05-01

    All-optical spiking neural networks would allow high speed parallelized processing of time-encoded information, using the same energy efficient computational principles as our brain. As the neurons in these networks need to be able to process pulse trains, they should be excitable. Using simulations, we demonstrate Class 1 excitability in optically injected microdisk lasers, and propose a cascadable optical spiking neuron design. The neuron has a clear threshold and an integrating behavior. In addition, we show that the optical phase of the input pulses can be used to create inhibitory, as well as excitatory perturbations. Furthermore, we incorporate our optical neuron design in a topology that allows a disk to react on excitations from other disks. Phase tuning of the intermediate connections allows to control the disk response. Additionally, we investigate the sensitivity of the disk circuit to deviations in driving current and locking signal wavelength detuning. Using state-of-the-art fabrication techniques for microdisk laser, the standard deviation of the lasing wavelength is still about one order of magnitude too large. Finally, as the dynamical behavior of the microdisks is identical to the behavior in Semiconductor Ring Lasers (SRL), we compare the excitability mechanism due to optically injection with the previously proposed excitability due to asymmetry in the intermodal coupling in SRLs, as the latter mechanism can also be induced in disks due to, e.g., asymmetry in the external reaction. In both cases, the symmetry between the two counter-propagating modes of the cavity needs to be broken to prevent switching to the other mode, and allow the system to relax to its initial state after a perturbation. However, the asymmetry due to optical injection results in an integrating spiking neuron, whereas the asymmetry in the intermodal coupling is known to result in a resonating spiking neuron.

  14. Astronomical Approach to Physical Science Curriculum

    NASA Astrophysics Data System (ADS)

    Manning, H. L. K.; Churukian, A. D.

    2004-11-01

    The Astronomical Approach to Physical Science Curriculum (AAPS Curriculum) is an innovative curriculum that incorporates an astronomy theme into an inquiry-based physical science curriculum for pre-service, elementary school teachers. Many physical science courses are a non-cohesive collection of topics required for the state teaching license. Through the use of astronomy and space science examples, the AAPS Curriculum will have a coherent theme that ties the wide variety of physical science topics together and provides many real world applications for the topics covered in the course. This new curriculum will incorporate the applications of knowledge to complete the learning cycle-exploration, concept introduction, application. Astronomy and space science applications will be emphasized throughout the curriculum. The theme of astronomy was chosen to prepare elementary school teachers for teaching astronomy and space science in their classroom, as this is a topic in which many school children are consistently interested. Since astronomy is a topic that can be used as a springboard to teach many other areas of study, we want teachers who are knowledgeable in topics of astronomy so they are capable of preparing creative lessons throughout their entire curriculum that are exciting to their students. The AAPS Curriculum will train college students to become teachers who are comfortable with physical science and astronomy topics and who are excited to teach these topics in their classroom. Funding for this work is provided by the IDEAS grant program of the Space Telescope Science Institute.

  15. Science Signaling Podcast: 06 May 2008

    NSDL National Science Digital Library

    Elizabeth M. Adler (American Association for the Advancement of Science; Science Signaling REV)

    2008-05-06

    This conversation is about research highlighted in Editors' Choice titled, "What’s So Exciting About Glia?" The highlighted article is R. Káradóttir, N. B. Hamilton, Y. Bakiri, D. Attwell, Spiking and nonspiking classes of oligodendrocyte precursor glia in CNS white matter. Nat. Neurosci. 11, 450–456 (2008). (Length: 6 min; file size: 2.61 MB; file format: mp3; location: http://podcasts.aaas.org/science_signaling/ScienceSignaling_080506.mp3)

  16. Earth Sciences Division annual report 1989

    SciTech Connect

    Not Available

    1990-06-01

    This Annual Report presents summaries of selected representative research activities from Lawrence Berkeley Laboratory grouped according to the principal disciplines of the Earth Sciences Division: Reservoir Engineering and Hydrology, Geology and Geochemistry, and Geophysics and Geomechanics. We are proud to be able to bring you this report, which we hope will convey not only a description of the Division's scientific activities but also a sense of the enthusiasm and excitement present today in the Earth Sciences.

  17. A Tree at Bedtime Investigation: Connecting Mathematics, Science, and Literature

    ERIC Educational Resources Information Center

    Kieff, Judith

    2006-01-01

    Activities that promote "active thinking" help children learn mathematics and science by allowing them to work at forming relationships, making connections, and integrating concepts and procedures. Dynamic and exciting children's books invite and motivate children to learn mathematics and science by responding to stories, characters, and their…

  18. Results from the Independent Evaluation of the Seminars on Science

    ERIC Educational Resources Information Center

    Stokes, Laura; St. John, Mark; Hirabayashi, Judy; Smith, Anita

    2007-01-01

    In 1998, the American Museum of Natural History (AMNH) launched an ambitious effort to create on-line science courses for K-12 educators that would immerse them in exciting science topics and give them access to the Museum's scientific resources (scientists, research, expeditions, collections, and exhibitions). This project, called Seminars on…

  19. Science Shorts: More than One Way to Investigate

    ERIC Educational Resources Information Center

    Coskie, Tracy L.; Davis, Kimberly J.

    2007-01-01

    An exciting element of science fairs is that they give students the opportunity to explore various interests through scientific investigation. Many students, however, mistakenly think that all investigations are experiments. This lesson can help broaden students' conceptions of science. (Contains 1 resource.)

  20. Optimization of Two-photon Excited Fluorescence Enhancement between Tunable and Broadband Femtosecond Laser Pulse Excitations

    E-print Network

    Wang, Chao

    2012-02-14

    -phantoms. Under environmental influences (mutual quenching through one-photon absorption(s) and solvent effect), multicolor TPEF enhancement observed from a mixture of the three dyes shows promise of sub-10 fs TLP as simultaneous excitation for multiple...

  1. Peroxyacetyl radical: electronic excitation energies, fundamental vibrational frequencies, and symmetry breaking in the first excited state.

    PubMed

    Copan, Andreas V; Wiens, Avery E; Nowara, Ewa M; Schaefer, Henry F; Agarwal, Jay

    2015-02-01

    Peroxyacetyl radical [CH3C(O)O2] is among the most abundant peroxy radicals in the atmosphere and is involved in OH-radical recycling along with peroxyacetyl nitrate formation. Herein, the ground (X?) and first (A?) excited state surfaces of cis and trans peroxyacetyl radical are characterized using high-level ab initio methods. Geometries, anharmonic vibrational frequencies, and adiabatic excitation energies extrapolated to the complete basis-set limit are reported from computations with coupled-cluster theory. Excitation of the trans conformer is found to induce a symmetry-breaking conformational change due to second-order Jahn-Teller interactions with higher-lying excited states. Additional benchmark computations are provided to aid future theoretical work on peroxy radicals. PMID:25662641

  2. Cognitive science Why cognitive science?

    E-print Network

    Sussex, University of

    courses are there? Neuroscience with Cognitive Science (p100) Philosophy and Cognitive Science (p102Cognitive science Why cognitive science? How does the mind work? What is the relation between mind and philosophical breakthroughs, and placing the notion of computation centre-stage, cognitive science offers

  3. Cognitive science Why cognitive science?

    E-print Network

    Sussex, University of

    breakthroughs ­ in psychology, neuroscience, philosophy and artificial intelligence (AI) ­ cognitive science) in Neuroscience with Cognitive Science (p111) BA (Hons) in Philosophy and Cognitive Science (p113) BSc (HonsCognitive science Why cognitive science? How does the mind work? What is the relation between mind

  4. Intelligent systems in biology: why the excitement?

    Microsoft Academic Search

    R. Lathrop

    2001-01-01

    Biology has rapidly become a data-rich, information-hungry science because of recent massive data generation technologies. Our biological colleagues are designing more clever and informative experiments because of recent advances in molecular science. These experiments and data hold the key to the deepest secrets of biology and medicine, but we cannot fully analyze this data due to the wealth and complexity

  5. Excitation and photon decay of giant resonances excited by intermediate energy heavy ions

    SciTech Connect

    Bertrand, F.E.; Beene, J.R.

    1987-01-01

    Inelastic scattering of medium energy heavy ions provides very large cross sections and peak-to-continuum ratios for excitation of giant resonances. For energies above about 50 MeV/nucleon, giant resonances are excited primarily through Coulomb excitation, which is indifferent to isospin, thus providing a good probe for the study of isovector giant resonances. The extremely large cross sections available from heavy ion excitation permit the study of rare decay modes of the giant resonances. In particular, recent measurements have been made of the photon decay of giant resonances following excitation by 22 and 84 MeV/nucleon /sup 17/O projectiles. The singles results at 84 MeV/nucleon yield peak cross sections for the isoscalar giant quadrupole resonance and the isovector giant dipole resonance of approximately 0.8 and 3 barns/sr, respectively. Data on the ground state decay of the isoscalar giant quadrupole and isovector giant dipole resonances are presented and compared with calculations. Decays to low-lying excited states are also discussed. Preliminary results from an experiment to isolate the /sup 208/Pb isovector quadrupole resonance using its gamma decay are presented. 22 refs., 19 figs., 1 tab.

  6. FOREWORD Nanomaterials science Nanomaterials science

    NASA Astrophysics Data System (ADS)

    Rohrer, Heinrich

    2010-10-01

    The nanometer regime covers the transition from condensed matter behavior to atomic and molecular properties and thus is a very rich but also very demanding area in materials science. Close to the condensed matter side, properties and functions might still very well be scalable, whereas close to the atomic and molecular side, the scalability is mostly lost. Properties and functions change qualitatively or quantitatively by orders of magnitude when the dimensions become smaller than a critical size in the nanometer range. Examples are the ballistic regime for electron or spin transport at dimensions below the mean free path, near-field effects in scanning near-field optical microscopy and quantum wells when the dimensions are below an appropriate wavelength, novel electronic, mechanical, and chemical properties when the number of bulk atoms becomes smaller than that of surface atoms, quantum conduction, and Coulomb blockade. Thus, by going below a certain size, an abundance of novel properties and functions are at one's disposal, or, in other words, we can functionalize materials simply by reducing their size to the nanoscale. The key to the future lies in the functions that we give to materials, not just in finding 'novel functional materials'. This catch expression in many materials science programs and initiatives of the past two decades sounds great, but it is not what really counts. All materials are functional in one way or another and, therefore, all new materials are 'novel functional materials'. Certainly, finding new materials is always an important part of progress, but we should also focus on the much larger domain of novel functions that we can give to existing or modified materials. A good example is semiconductors: they are fifty or more years old and their properties are very well known, but they were not of widespread interest and use until the transistor changed their destiny into being the central material in the information technology revolution. Interfaces gave them their functions, and shaping them into ever-smaller functional components made them indispensably omnipresent as transistors—produced in billions per person and per year—and they are no doubt the rulers of today's technical world. The semiconductor and transistor serve as an inspiring example of functionalizing materials. The developments of microelectronics profited very much from scalability, that is, the properties and functions do not change significantly with size. Therefore, every step toward smaller dimensions was a technical and commercial challenge with risks well under control. The transition to the nanoscale, however, is discontinuous. Examples of this transition are the local probe methods that exploit the mechanically controlled proximity to the object under consideration and that have become indispensable as microscopes and as measuring and modifying tools, the size of molecular components that are much smaller than the smallest possibly achievable transistor, the properties and functions of materials below a critical size as mentioned above, the continuum properties versus discrete ones, and novel concepts inspired by living nature. Those novel concepts include growing circuits first and building the active components at the nodes afterwards and measuring weak by weak, small by small, and many by many. It is these discontinuous steps that make the nanoscale different, not just smaller. They pose exciting challenges, open great opportunities and nearly unlimited possibilities, but they also carry serious technical, commercial, environmental, and health risks. The nanoscale is also a great opportunity for materials science in general. Materials science is interdisciplinary per se. A materials scientist should have a reasonable understanding of physics, chemistry, engineering, and more recently, also biology. Certainly one can always team up with representatives from other disciplines and forge collaborations. However, an effective team can only emerge from a common understanding of the respective languages and problems. Th

  7. Science Teaching to Fire the Imagination.

    ERIC Educational Resources Information Center

    Sandford, Diana; Fleetwood, Julie

    1997-01-01

    Presents a range of exciting ideas for encouraging active learning, for illuminating new concepts, and for making science lessons fun. Topics include modeling, matter, heat, diffusion, changes of state, heat transfer, energy changes, atomic structure, waves, gravity, enzymes, and habitats. (JRH)

  8. The Future of Nuclear Science in Australia

    SciTech Connect

    Dillich, Jack [Australian Nuclear Science and Technology Organisation (ANSTO), PMB 1 Menai, NSW 2234, New South Wales (Australia)

    2002-07-01

    The replacement of Australia's only nuclear reactor, the 44 year old HIFAR, with a state-of-the-art research facility represents an exciting development in nuclear science. The design for the replacement reactor incorporates many safety features, including extraordinary defence-in-depth. The facilities will include advanced capabilities in the areas of radiopharmaceutical production and neutron scattering research. (author)

  9. Faculty of Science & Health SCHOOL OF NURSING

    E-print Network

    Humphrys, Mark

    Faculty of Science & Health SCHOOL OF NURSING Lecturer in Mental Health Nursing (5 year contract university based School of Nursing that is closely associated with a number of partner health services. This is a very exciting time in the development of nursing practice, nursing research and education in Ireland

  10. Communicating Science

    NASA Astrophysics Data System (ADS)

    Russell, Nicholas

    2009-10-01

    Introduction: what this book is about and why you might want to read it; Prologue: three orphans share a common paternity: professional science communication, popular journalism, and literary fiction are not as separate as they seem; Part I. Professional Science Communication: 1. Spreading the word: the endless struggle to publish professional science; 2. Walk like an Egyptian: the alien feeling of professional science writing; 3. The future's bright? Professional science communication in the age of the internet; 4. Counting the horse's teeth: professional standards in science's barter economy; 5. Separating the wheat from the chaff: peer review on trial; Part II. Science for the Public: What Science Do People Need and How Might They Get It?: 6. The Public Understanding of Science (PUS) movement and its problems; 7. Public engagement with science and technology (PEST): fine principle, difficult practice; 8. Citizen scientists? Democratic input into science policy; 9. Teaching and learning science in schools: implications for popular science communication; Part III. Popular Science Communication: The Press and Broadcasting: 10. What every scientist should know about mass media; 11. What every scientist should know about journalists; 12. The influence of new media; 13. How the media represents science; 14. How should science journalists behave?; Part IV. The Origins of Science in Cultural Context: Five Historic Dramas: 15. A terrible storm in Wittenberg: natural knowledge through sorcery and evil; 16. A terrible storm in the Mediterranean: controlling nature with white magic and religion; 17. Thieving magpies: the subtle art of false projecting; 18. Foolish virtuosi: natural philosophy emerges as a distinct discipline but many cannot take it seriously; 19. Is scientific knowledge 'true' or should it just be 'truthfully' deployed?; Part V. Science in Literature: 20. Science and the Gothic: the three big nineteenth-century monster stories; 21. Science fiction: serious literature of ideas or low-grade entertainment?; 22. Science in British literary fiction; 23. Science on stage: the politics and ethics of science in cultural and educational contexts.

  11. Faculty of Science: EARTH SCIENCES

    E-print Network

    Brownstone, Rob

    Faculty of Science: EARTH SCIENCES Possible Careers Geologist Geochemist Geophysicist Mining - www.gac.ca Canadian Federation of Earth Sciences - www.geoscience.ca Canadian Geotechnical Society Respect the Earth Majors & Careers www.dal.ca/careerinfo #12;

  12. Design of a circuit for measuring the lifetimes of excited nuclear states of the order of nanoseconds 

    E-print Network

    Kuritzky, Clarence Samuel

    1964-01-01

    DESIGN OF A CIRCUIT FOR MEASURING THE LIFETIMES OF EXCITED NUCLEAR STATES OF THE ORDER OF NANOSECONDS A Thesis By CLARENCE SAMUEL KURITZKY Submitted to the Graduate College of the Texas AS, M University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE January 1964 Ma 1 or Sub) ect: Phys ic s DESIGN OF A CIRCUIT FOR MEASURING THE LIFETIMES OF EXCITED NUCLEAR STATES OF THE ORDER OF NANOSECONDS A Thesis By CLARENCE SAMUEL KURITZKY Approved as to style...

  13. Physics and the Philosophy of Science at the Turn of the Twentieth Century

    E-print Network

    Howard, Don

    Physics and the Philosophy of Science at the Turn of the Twentieth Century (Forthcoming Theoretical physics and the philosophy of science are among the most important fields of research, and the philosophy of science had become in centers like Vienna and Berlin a self-assertive and exciting new field

  14. University of Maryland NSFMRSEC Highlight Annual Middle School Student Science Conference (SSC)

    E-print Network

    Rubloff, Gary W.

    University of Maryland NSFMRSEC Highlight Annual Middle School Student Science Conference (SSC May 2009 marked the University of Maryland MRSEC's 12th Annual Middle School Student Science excited about science. ·Increasing Student Interest in STEM in High School·Increasing Student Interest

  15. Local Investigation in Dynamic Behavior of Excited Water Nanoclusters on Cu(111) Surface

    NASA Astrophysics Data System (ADS)

    Guo, Yang; Gong, Huiqi; Dong, Li; Li, Lailai; Wang, Jinchuan; Shan, Xinyan; Lu, Xinghua

    2014-03-01

    Dynamic behavior of water molecules on surfaces is important for surface-mediated water dissociations and reactions. Here we present investigations in dynamic behavior of excited water nanoclusters on Cu (111) surface by using a low temperature scanning tunneling microscope (STM). It is found that excess electrons in a single water nanocluster can be injected from a metallic STM tip under a positive voltage. Such injection of electrons results in both the diffusion of single H2O molecules within the nanocluster and directional diffusion of water nanoclusters on surface. The range of lateral diffusion is limited to several nanometers from the tip because of the electrical screening effect from Cu substrate for the excess electrons in the nanocluster. In addition, femto-second laser pulses are employed to excite the water nanoclusters during STM imaging with tip in the tunneling condition. Significant changes in topographic profile of H2O nanoclusters are observed under the photoexciation, as compared with that of the nanoclusters in the ground state. The results obtained in this study provide a microscopic understanding of the diffusion mechanism of excited water nanoclusters on surface. the National Science Foundation of China (Grant No. 11174347, 61376100) and the Ministry of Science and Technology of China (Grant No. 2012CB933002).

  16. Excitation of millimeter and submillimeter water masers

    NASA Technical Reports Server (NTRS)

    Neufeld, David A.; Melnick, Gary J.

    1991-01-01

    The excitation of maser emission in millimeter and submillimeter transitions of interstellar and circumstellar water is considered. An escape probability method is used to determine the equilibrium populations in 349 rotational states of both ortho- and para-water under varying conditions of gas temperature, density, water abundance, and radiation field. It is shown that, under those conditions believed to prevail around late-type stars and within star-forming regions, strong millimeter and submillimeter water maser emission can be generated by collisional excitations by H2. Several maser transitions can have strengths close to that of the 22 GHz line. The water maser line which can be observed from mountaintop facilities and those which will require air- or space-borne platforms are indicated. The exact portion of parameter space in which each maser transition exhibits peak emission is shown.

  17. String excitation inside generic black holes

    E-print Network

    Maeda, K I; Narita, M; Maeda, Kengo; Torii, Takashi; Narita, Makoto

    2000-01-01

    We calculate how much a first-quantized string is excited after crossing the inner horizon of charged Vaidya solutions, as a simple model of generic black holes. To quantize a string suitably, we first show that the metric is approximated by a {\\it plane-wave} metric near the inner horizon when the surface gravity of the horizon $\\kappa_I$ is small enough. Next, it is analytically shown that the string crossing the inner horizon is excited infinitely in an asymptotically flat spacetime, while it is finite in an asymptotically de Sitter spacetime and the string can pass across the inner horizon when $\\kappa_I<2\\kappa:= 2 {min}\\{\\kappa_B,\\kappa_C \\}$, where event horizon. This implies that the strong cosmic censorship holds in an asymptotically flat spacetime, while it is violated in an asymptotically de Sitter spacetime from the point of view of string theory.

  18. Viscous flow drag reduction by acoustic excitation

    NASA Technical Reports Server (NTRS)

    Nagel, Robert T.

    1986-01-01

    An experimental program in which the effectiveness of a single large eddy break up (LEBU) blade is enhanced by proper acoustic excitation is described. Acoustic waves are generated in response to the incident large scale eddies and directed at the blade trailing edge through the test surface floor below the manipulator blade. The acoustic input is phase locked to the incident flow. Control of the acoustic input apparently allows enhancement of the large eddy cancellation process leading to a decrease of skin friction coefficient. Control of this process with acoustic excitation indicates that vortex unwinding is the mechanism for large eddy destruction in the boundary layer. A deeper understanding of this phenomena could lead to better drag reduction technology and further understanding of the physics of the turbulent boundary layer.

  19. Localized excitations in UPdSn

    NASA Astrophysics Data System (ADS)

    Nakotte, H.; Bull, M.; McEwen, K. A.; Robinson, R. A.; Swan, T.; Kelley, T. M.; Eccleston, R. S.; Brück, E.

    1998-04-01

    We have measured the inelastic-neutron-scattering response of UPdSn using the HET and PHAROS spectrometers at the ISIS and LANSCE facilities, respectively. UPdSn shows some quasielastic scattering, which may be attributed to the hybridization of the 5f-electrons with the conduction electrons. We also find a clear excitation around 40 meV above 40 K. This excitation may be indicative of localized crystal fields in UPdSn, but its strong temperature dependence seems to contradict a simple crystal-field picture. Below TN, an unusual temperature dependence may be attributed to magnetically driven distortions (and subsequent changes in the local surrounding of the U-ions), but there is some evidence that other additional mechanism(s) may contribute above TN.

  20. Localized excitations in UPdSn

    NASA Astrophysics Data System (ADS)

    Nakotte, H.; Bull, M.; McEwen, K. A.; Robinson, R. A.; Swan, T.; Kelley, T. M.; Eccleston, R. S.; Brück, E.

    We have measured the inelastic-neutron-scattering response of UPdSn using HET and PHAROS spetrometers at the ISIS and LANSCE facilities, respectively. UPdSn shows some quasielastic scattering, which may be attributed to the hybridization of the 5f-electrons with the conduction electrons. We also find a clear excitation around 40 meV above 40 K. This excitation may be indicative of localized crystal fields in UPdSn, but its strong temperature dependence seems to contradict a simple crystal-field picture. Below TN, an unusual temperature dependence may be attributed to magnetically driven distortions (and subsequent changes in the local surrounding of the U-ions), but there is some evidence that other additional mechanim(s) may contribute above TN.

  1. Localized excitations in UPdSn

    SciTech Connect

    Nakotte, H.; Robinson, R.A.; Swan, T.; Kelley, T. [Los Alamos National Lab., NM (United States). Manuel Lujan Jr. Neutron Scattering Center; Bull, M. [Univ. of London (United Kingdom); [Univ. of Amsterdam (Netherlands). Van der Waals-Zeeman Inst.; McEwen, K.A. [Univ. of London (United Kingdom); Ecclestone, R.A. [Rutherford Appleton Lab., Chilton (United Kingdom). ISIS Div.; Brueck, E. [Univ. of Amsterdam (Netherlands). Van der Waals-Zeeman Inst.

    1997-11-01

    The authors have measured the inelastic neutron-scattering response of UPdSn at various temperatures using the HET and PHAROS spectrometers at the ISIS and MLNSC facilities, respectively. UPdSn shows some quasielastic scattering, which may be attributed to the hybridization of the 5f electrons with the conduction electrons. Furthermore, they find a clear excitation around 40meV above 40K in addition to the phonon contribution. While this excitation may be indicative of crystal fields in UPdSn, its strong temperature dependence seems to contradict a simple crystal-field picture. Below T{sub N}, the unusual temperature dependence may be attributed to magnetically-driven distortions (and subsequent changes in the local surrounding of the U ions), but there is some evidence that other additional mechanism(s) may contribute above T{sub N}. Some possible mechanisms will be discussed.

  2. Ultrafast evolution of imidazole after electronic excitation.

    PubMed

    Montero, Raúl; Peralta Conde, Álvaro; Ovejas, Virginia; Fernández-Fernández, Marta; Castaño, Fernando; Longarte, Asier

    2012-11-01

    The ultrafast dynamics of the imidazole chromophore has been tracked after electronic excitation in the 250-217 nm energy region, by time delayed ionization with 800 nm laser pulses. The time-dependent signals collected at the imidazole(+) mass channel show the signature of femtosecond dynamics, originating on the ??*- and ??*-type states located in the explored energy region. The fitting of the transients, which due to the appearance of nonresonant coherent adiabatic excitation requires a quantum treatment based in the Bloch equations, yields two lifetimes of 18 ± 4 and 19 ± 4 fs. The first is associated with the ??* ? ??* internal conversion, while the second reflects the loss of ionization cross-section as the system evolves along the dissociative ??* surface. This study provides a comprehensive picture of the photophysics of the molecule that agrees with previous experimental and theoretical findings. PMID:23088353

  3. Resonant inclination excitation of migrating giant planets

    E-print Network

    Edward W. Thommes; Jack J. Lissauer

    2003-08-07

    The observed orbits of extrasolar planets suggest that many giant planets migrate a considerable distance towards their parent star as a result of interactions with the protoplanetary disk, and that some of these planets become trapped in eccentricity-exciting mean motion resonances with one another during this migration. Using three-dimensional numerical simulations, we find that as long as the timescale for damping of the planets' eccentricities by the disk is close to or longer than the disk-induced migration timescale, and the outer planet is more than half the mass of the inner, resonant inclination excitation will also occur. Neither the addition of a (simple, fixed) disk potential, nor the introduction of a massive inner planetary system, inhibit entry into the inclination resonance. Therefore, such a mechanism may not be uncommon in the early evolution of a planetary system, and a significant fraction of exoplanetary systems may turn out to be non-coplanar.

  4. The self-excited axisymmetric jet

    NASA Technical Reports Server (NTRS)

    Hasan, M. A. Z.; Hussain, A. K. M. F.

    1982-01-01

    The results of a number of investigations suggest that large-scale coherent structures and their interactions play key roles in the transport of heat, mass, and momentum, and in the generation of aerodynamic noise. Investigations related to the study of a large-scale coherent structure in the circular jet are considered, taking into account the advantages of inducing controlled perturbation through self-sustained excitation with the whistler nozzle. The primary objective of the present study was to document the jet response to self-excitation and the sensitivity of this response to the initial condition and the Reynolds number R(D). It was also felt that the results would find use in the control of mixing and aerodynamic noise in a jet.

  5. Quantum fluctuations and excitations in antiferromagnetic quasicrystals

    SciTech Connect

    Wessel, Stefan [Institut fuer Theoretische Physik III, Universitaet Stuttgart, D-70550 Stuttgart (Germany); Milat, Igor [Theoretische Physik, ETH Zuerich, CH-8093 Zurich (Switzerland)

    2005-03-01

    We study the effects of quantum fluctuations and the excitation spectrum for the antiferromagnetic Heisenberg model on a two-dimensional quasicrystal, by numerically solving linear spin-wave theory on finite approximants of the octagonal tiling. Previous quantum Monte Carlo results for the distribution of local staggered magnetic moments and the static spin structure factor are reproduced well within this approximate scheme. Furthermore, the magnetic excitation spectrum consists of magnonlike low-energy modes, as well as dispersionless high-energy states of multifractal nature. The dynamical spin structure factor, accessible to inelastic neutron scattering, exhibits linear-soft modes at low energies, self-similar structures with bifurcations emerging at intermediate energies, and flat bands in high-energy regions. We find that the distribution of local staggered moments stemming from the inhomogeneity of the quasiperiodic structure leads to a characteristic energy spread in the local dynamical spin susceptibility, implying distinct nuclear magnetic resonance spectra, specific for different local environments.

  6. Multiflavour excited mesons from the fifth dimension

    E-print Network

    Angel Paredes; Pere Talavera

    2004-12-21

    We study the Regge trajectories and the quark-antiquark energy in excited hadrons composed by different dynamical mass constituents via the gauge/string correspondence. First we exemplify the procedure in a supersymmetric system, D3-D7, in the extremal case. Afterwards we discuss the model dual to large-Nc QCD, D4-D6 system. In the latter case we find the field theory expected gross features of vector like theories: the spectrum resembles that of heavy quarkonia and the Chew-Frautschi plot of the singlet and first excited states is in qualitative agreement with those of lattice QCD. We stress the salient points of including different constituents masses.

  7. Sodium UV modeless laser excitation for PLGS

    NASA Astrophysics Data System (ADS)

    Moldovan, I. C.; Fesquet, V.; Marc, F.; Guillet de Chatellus, H.; Pique, J.-P.

    In the framework of Laser Guide Star projects and more particularly of VASAO project of the Canada France Hawaii Telescope, we have developed a modeless laser at 330 nm and we have carried out photometry experiments in laboratory, in order to evaluate the feasibility of the sodium atom excitation at 330 nm. Our modeless laser is a DCM dye laser frequency doubled by a BBO crystal. A high efficiency acousto-optical crystal assures the modeless property. We present the experimental results of sodium atom excitation of 3S{1/2} to 4P{3/2} transition at 330.24 nm and 3S{1/2} to 3P{3/2} transition at 589 nm. The rate equation model gives a good interpretation of the experimental results.

  8. Excited binomial states for the pseudoharmonic oscillator

    NASA Astrophysics Data System (ADS)

    Popov, Du?an; Pop, Nicolina; Maria, Robert

    2012-08-01

    We have examined some properties of a linear superposition of the binomial states (BSs), in the basis of Fock - vectors which correspond to the pseudoharmonic oscillator (PHO). These states have all the properties of usual coherent states (CSs). We have defined the excited binomial states (EBSs) for the PHO, by repeatedly application of the SU(1, 1) raising operator on the non-excited BSs, which is considered the "fundamental" state. Also we have examined the expectation values in the EBSs - basis, especially of the integer powers of the number operator, which is useful to calculate the Mandel's parameter. Depending on the value of this parameter, we can conclude about the statistical behavior of the EBCs: sub-Poissonian, Poissonian or super-Poissonian.

  9. Nuclear level excitation during charge nonconservation

    SciTech Connect

    Holjevic-acute-accent, S.; Logan, B.A.; Ljubiic-acute-accent, A.

    1987-01-01

    The possibility of nuclei being excited during charge nonconservation was investigated. The process studied is analogous to nuclear K capture which does not change a nucleon's charge state but which does leave the nucleus in an excited state. We searched for ..gamma.. rays emitted by /sup 127/I nuclei and detected in a 25.4 cm x 20.3 cm diam NaI(Tl) counter. Our most conservative limit for the charge nonconserving lifetime tau/sub CNC/ for this mechanism is tau/sub CNC/greater than or equal to1.9 x 10/sup 21/ yr. The results can be used to place limits on the charge nonconservation mechanism in weak interactions where a neutrino replaces an electron in the (e,e) current, and where a proton replaces a neutron in the (p,n) current.

  10. Excitation processes in H--Kr collisions

    NASA Astrophysics Data System (ADS)

    Esaulov, V. A.; Grouard, J. P.; Hall, R. I.; Montmagnon, J. L.

    1987-03-01

    An electron spectroscopy study of H--Kr collisions in the 20-500-eV collision energy range revealed the excitation of (2s2) 1S, (2p2) 1D, and (2s2p) 1P states of H- and of the (5s2) 2P3/2,1/2 Kr- state. The angular distribution of electrons produced from the decay of these states is reported. An anisotropic distribution for the (2s2) 1S state is observed at these energies as was previously reported for H- collisions with He, Ar, and H2 by Risley and co-workers [Phys. Rev. A 9, 1115 (1974) and IEEE Trans. Nuc. Sci. NS26, 1027 (1979)]. Relative cross sections for the excitation of these states are deduced from the angular distributions.

  11. Giant transmission Goos–Hänchen shift in surface plasmon polaritons excitation and its physical origin

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Liu, Ju; Li, Zhi-Yuan

    2015-07-01

    Excitation of surface plasmon polaritons (SPPs) propagating at the interface between a dielectric medium and a silver thin film by a focused Gaussian beam in a classical Kretschmann prism setup is studied theoretically. We find that the center of the transmitted Gaussian evanescent wave has a giant lateral shift relative to the incident Gaussian beam center for a wide range of incident angle and Gaussian beam wavelength to excite SPPs, which can be more than two orders of magnitude larger than the silver film thickness. The phenomenon is closely related with the conventional Goos–Hänchen effect for total internal reflection of light beam, and it is called the transmission Goos–Hänchen shift. We find that this lateral shift depends heavily on the excitation wavelength, incident angle, and the silver layer thickness. Finite-difference time-domain simulations show that this transmission Goos–Hänchen shift is induced by a unique dynamical process of excitation, transport, and leakage of SPPs. Project supported by the National Basic Research Program of China (Grant No. 2013CB632704) and the National Natural Science Foundation of China (Grant No. 11374357).

  12. Orientational relaxation and vibrational excitation transfer in methanolcarbon tetrachloride solutions

    E-print Network

    Fayer, Michael D.

    Orientational relaxation and vibrational excitation transfer in methanol­carbon tetrachloride tetrachloride has been utilized to investigate orientational relaxation and vibrational excitation transfer constant. The biexponential anisotropy decay has been analyzed with a restricted orientational diffusion

  13. 69. Credit TCL. Housing of Pelton exciter impulse wheel and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    69. Credit TCL. Housing of Pelton exciter impulse wheel and attached General Electric 60 kW exciter generator. - Battle Creek Hydroelectric System, Battle Creek & Tributaries, Red Bluff, Tehama County, CA

  14. Monitoring Fluorescence in Cultured Neural Networks using Polymer Waveguide Excitation

    Microsoft Academic Search

    R. A. Seger; D. G. Rabus; Y. Ichihashi; M. Bruendel; J. Hieb; M. S. Isaacson

    2007-01-01

    We present fluorescence excitation of cultured living neural cells using integrated optical waveguides. The waveguides (width 5, 7, 9 mum) are fabricated in polymethylmethacrylate (PMMA) using deep ultraviolet radiation. The excitation wavelength is 473 nm.

  15. 13. POWERHOUSE INTERIOR, DETAIL OF EXCITER No. 2 GENERAL ELECTRIC ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. POWERHOUSE INTERIOR, DETAIL OF EXCITER No. 2 GENERAL ELECTRIC INDUCTION MOTOR NAMEPLATE. VIEW TO EAST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA

  16. 14. POWERHOUSE INTERIOR, EXCITER No. 2 SHOWING GENERAL ELECTRIC INDUCTION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. POWERHOUSE INTERIOR, EXCITER No. 2 SHOWING GENERAL ELECTRIC INDUCTION MOTOR IN SERIES BETWEEN PELTON-DOBLE IMPULSE WHEEL AND GENERAL ELECTRIC GENERATOR. VIEW TO EAST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA

  17. Photoexcited carrier dynamics and impact-excitation cascade in graphene

    E-print Network

    Tielrooij, Klaas J.

    In materials with strong electron-electron interactions, photoexcitation can trigger a cascade in which multiple particle-hole excitations are generated. Here we analyze the cascade of impact-excitation processes in graphene ...

  18. Stimulated Raman scattering imaging by continuous-wave laser excitation

    E-print Network

    Cheng, Ji-Xin

    microscopy [8]. By cw laser excitation, SRS spectroscopy of liquid benzene was shown in 1977 [9]. Recently]. In this work, SRS imaging of biologi- cal tissue by using cw lasers as excitation sources is demonstrated

  19. Ship Rolling Motion Subjected to Colored Noise Excitation 

    E-print Network

    Jamnongpipatkul, Arada

    2012-02-14

    in the probability?s view. The random differential equation of ships? rolling motion is established considering the nonlinear damping, nonlinear restoring moment, the white noise wave excitation, and the colored noise wave excitation. As an example, an ocean survey...

  20. Low Energy Excitations in Quantum Condensates

    NASA Astrophysics Data System (ADS)

    Baraban, Mara S.

    In this thesis, we theoretically study low energy excitations in two types of quantum condensates, Bose-Einstein condensates and Quantum Hall condensates. First, we investigate the effect of an anisotropic trap on the instability of the polar (mF = 0) phase of a spin-1 Bose-Einstein condensate. By rigorously considering the spatial quantization, we show that the growth of the nascent ferromagnetic phase at short times becomes anisotropic with stronger oscillations in the magnetization correlation function along the unconfined direction. Turning to quantum Hall condensates, we analyze edge excitations in the nu = 1 plateau and demonstrate that two experimentally observed features of edge modes, rapid head decay and long-lived charged excitations, cannot be consistently explained using a model where energy is dissipated from a hard edge via either phonon interactions or bulk AC conductivity. We suggest a soft edge model where heat can decay through intra-edge interactions to explain the discrepancy and calculate the scaling properties of this model. We then demonstrate numerically that non-Abelian quasihole excitations of the nu = 5/2 fractional quantum Hall state have some of the key properties necessary to support quantum computation. We find that as the quasihole spacing is increased, the two orthogonal wavefunctions describing a system with four quasiholes become exponentially degenerate with decay length xiE?2.3?0. Additionally we determine which fusion channel is lower in energy when two quasiholes are brought close together. Finally, we consider a hypothetical topological quantum computer composed of either Ising or Fibonacci anyons. For each case, we calculate the time and number of qubits necessary to execute the most computationally expensive step of Shor's quantum factoring algorithm, modular exponentiation. With reasonable restrictions on the physical parameters we find that factoring a 128 bit number requires approximately 103 Fibonacci anyons versus at least 3 x 109 Ising anyons.

  1. Excitation of a slow wave structure

    SciTech Connect

    Zhang Peng; Lau, Y. Y. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Hoff, Brad; French, D. M. [Air Force Research Laboratory, Kirtland AFB, Albuquerque, New Mexico 87117 (United States); Luginsland, J. W. [Air Force Office of Scientific Research, Arlington, Virginia 22203 (United States)

    2012-12-15

    The Green's function on a slow wave structure is constructed. The Green's function includes all radial modes, and for each radial mode, all space harmonics. We compare the analytic solution of the frequency response on the slow wave structure with that obtained from a particle-in-cell code. Favorable comparison is obtained when the first few lower order modes are resonantly excited. This gives some confidence in the prediction of converting a pulse train into radiation using a slow wave structure.

  2. Magnetic performance of a fast excitation wiggler

    SciTech Connect

    Gallardo, J.C.; Romano, T.; van Steenbergen, A.

    1993-03-01

    With the objective of performing an inverse free-electron laser accelerator experiment, an iron dominated (Vanadium Permendur), fast excitation, high K planar wiggler has been built and measured. The authors present in this report an analysis of a constant period wiggler and several tapering configurations (gap=4 mm; 3.0 cm < {lambda}{sub {omega}} < 5. cm) when they are driven to a peak field of B{sub max} {approx}1.4 T.

  3. Electron excitation cross sections for Si XII

    Microsoft Academic Search

    S. Kastner; C. Wade; T. S. Smith; M. Blaha

    1972-01-01

    Excitation cross sections are calculated for Si XII by the coulomb-Born method, using numerical Hartree-Fock radial functions. The transitions considered are 2s-np, ns-n'd, 2p-nd and 3s-np. Reasonable agreement with the general results of Bely and Petrini is obtained, but an appreciable difference occurs for 2s-7p. The effect of including higher multipoles in the coulomb-Born method is illustrated. For comparison, the

  4. Detecting Breather Excitations with Inelastic Tunneling Spectroscopy

    E-print Network

    Jian-Xin Zhu; K. O. Rasmussen; A. R. Bishop; A. V. Balatsky

    2004-07-08

    We propose inelastic electron tunneling spectroscopy scanning tunneling microscopy (IETS-STM) as a means of exciting and observing intrinsic localized modes (breathers) in a macromolecule. As a demonstration, inelastic tunneling features of the density of states are calculated for a simple nonlinear elastic Morse chain. The general formalism we have developed for the IETS is applicable to other nonlinear extended objects, such as DNA on a substrate.

  5. Photocycloaddition of anthracene to excited C-60

    SciTech Connect

    Gol`dshleger, N.F.; Denisov, N.N.; Lobach, A.S. [and others

    1995-02-01

    The ability to participate in photochemical cycloaddition reactions is characteristic feature of chromophores with a carbon double bond. In this work, the authors demonstrate the formation of an adduct by cycloaddition of anthracene to the triplet-excited C-60 fullerene under anaerobic conditions, which provides a straight forward way to synthesize new derivatives of C-60 fullerenes. Reaction methods, conditions, and mechanisms are included along with the characterization of the fullerene derivative with IR, MS, and NMR methods.

  6. STM-excited luminescence on organic materials

    Microsoft Academic Search

    S. F. Alvarado; L. Libioulle; P. F. Seidler

    1997-01-01

    A scanning tunneling microscope (STM) is used to generate electroluminescence from thin films of tris(8-hydroxyquinolato) aluminum (Alq3) deposited on Au(111) substrates. The emission spectra are highly dependent on the local structural features of the thin film. Furthermore, the intensity distribution is modulated by the collective charge-carrier excitations of the tip and the substrate. This is manifested as a red-shifted emission

  7. Control of a Separately Excited DC Machine

    Microsoft Academic Search

    Werner Leonhard

    \\u000a In Chap. 5 the steady state and dynamic behaviour of a separately excited DC machine with adjustable armature and field voltage\\u000a has been explained; this discussion is now extended by considering the machine as part of a feedback control system. The reason\\u000a for this is that in practice the choice of a DC drive is normally motivated by the possibility

  8. Bifurcations in dynamical systems with parametric excitation

    Microsoft Academic Search

    Siti Fatimah

    2002-01-01

    This thesis is a collection of studies on coupled nonconservative oscillator\\u000asystems which contain an oscillator with parametric excitation. The emphasis\\u000athis study will, on the one hand, be on the bifurcations of the simple\\u000asolutions such as fixed points and periodic orbits, and on the other hand on\\u000aidentifying more complicated dynamics, such as chaotic solutions.\\u000aWe study an

  9. Incessant excitation of the Earth's free oscillations

    Microsoft Academic Search

    K. Nawa; N. Suda; Yoshio Fukao; Tadahiro Sato; Yuichi Aoyama; Kazuo Shibuya

    1998-01-01

    We, for the first time, report the evidence of incessant excitation of the Earth's free oscillations, mainly the fundamental spheroidal modes in a frequency range from 0.3 to 5 mHz, based on the three year record of a superconducting gravimeter at Syowa Station, East Antarctica. The frequency-time spectrogram of this record is striped by more than 30 lines at nGal

  10. Photon excitation of sodium emission in Comets

    Microsoft Academic Search

    E. A. Baranovsky; V. P. Tarashchuk

    2004-01-01

    We consider the possibility of the excitation of sodium resonance emission in cometary matter under solar radiation at a heliocentric\\u000a distance of 5 AU, as was observed when a fragment of Comet Shoemaker-Levy 9 plunged into Jupiter. When the sodium emission\\u000a is calculated, the multiple scattering in the cometary cloud is taken into account. We use a non-LTE radiative transfer

  11. Multiflavour excited mesons from the fifth dimension

    Microsoft Academic Search

    Angel Paredes; Pere Talavera

    2005-01-01

    We study the Regge trajectories and the quark–antiquark energy in excited hadrons composed by different dynamical mass constituents via the gauge\\/string correspondence. First we exemplify the procedure in a supersymmetric system, D3–D7, in the extremal case. Afterwards we discuss the model dual to large-Nc QCD, D4–D6 system. In the latter case we find the field theory expected gross features of

  12. Collisional excitation of interstellar methyl cyanide

    NASA Technical Reports Server (NTRS)

    Green, Sheldon

    1986-01-01

    Theoretical calculations are used to determine the collisional excitation rates of methyl cyanide under interstellar molecular cloud conditions. The required Q(L,M) as a function of kinetic temperature were determined by averaging fixed energy IOS (infinite order sudden) results over appropriate Boltzmann distributions of collision energies. At a kinetic temperature of 40 K, rates within a K ladder were found to be accurate to generally better than about 30 percent.

  13. Collisional excitation of interstellar methyl cyanide

    SciTech Connect

    Green, S.

    1986-10-01

    Theoretical calculations are used to determine the collisional excitation rates of methyl cyanide under interstellar molecular cloud conditions. The required Q(L,M) as a function of kinetic temperature were determined by averaging fixed energy IOS (infinite order sudden) results over appropriate Boltzmann distributions of collision energies. At a kinetic temperature of 40 K, rates within a K ladder were found to be accurate to generally better than about 30 percent. 11 references.

  14. Multiphonon excitations in boson quantum films

    SciTech Connect

    Clements, B.E. [Institute Laue Langevin, 38042 Grenoble Cedex (France)] [Institute Laue Langevin, 38042 Grenoble Cedex (France); [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States); Krotscheck, E. [Institut fuer Theoretische Physik, Johannes Kepler Universitaet, A-4040 Linz (Austria)] [Institut fuer Theoretische Physik, Johannes Kepler Universitaet, A-4040 Linz (Austria); [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States); Tymczak, C.J. [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States)] [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States)

    1996-05-01

    Dynamical excitations in thin liquid films of {sup 4}He adsorbed to a substrate are investigated by using a microscopic theory of excitations that includes multiple-phonon scattering. We study the dispersion relation, excitation mechanisms, transition densities, and particle currents as a function of surface coverage. A primary new result is that we have included three-phonon scattering processes in the calculation of the dynamic structure function and the one-body current densities. With the exception that our ground state is determined by our variational theory, rather than taken from experiment, our work on the dynamic structure function is the generalization of that of Jackson [Phys. Rev. A {bold 4}, 2386 (1971)] to inhomogeneous systems (films). Using sum rules for the dynamic structure function as a guide, we suggest a simple scaling argument for improving the agreement between our dynamic structure function and the experimental one. The addition of three-phonon contributions bring about the following changes. First, the energy of most modes is lowered by a non-negligible amount for finite momentum excitations. Second, the film{close_quote}s surface mode is the exception; it is only slightly affected. Third, for monolayer films there is large scattering at high energies at intermediate values of momenta. This scattering can be traced back to an anomalously large contribution to the two-particle density of states. Fourth, all modes with energy above a critical energy decay, and the associated peaks of the dynamic structure function are broadened. Fifth, the maxonlike character is enhanced in the bulklike modes. {copyright} {ital 1996 The American Physical Society.}

  15. Spatial Profiles of Excitation in Helium

    Microsoft Academic Search

    Zeljka Nikitivic; Gordana Malovic; Aleksandra Strinic; Petrovic Zoran

    2003-01-01

    In this paper we present electron ionization and excitation (and emission) coefficients for several lines of helium. We use drift tube technique for measuring absolute emission intensities in low-current self-sustained Townsend type discharges. In the experiment current was limited to less than 2muA to maintain uniform field conditions. The data were obtained from moderate E\\/N of 100 Td, where electrons

  16. Photodissociation and rotational excitation of interstellar CO

    Microsoft Academic Search

    S. Warin; J. J. Benayoun; Y. P. Viala

    1996-01-01

    We have developed a detailed interstellar cloud model that takes into account the chemistry among simple carbon and oxygen bearing molecules, as well as ^13^C and ^18^O isotopic compounds. The rotational population of H_2_, CO, ^13^CO and C^18^O and the fine structure excitation of C, C^+^ and O are controlled by chemical processes, including selective photodissociation which depends on the

  17. Excitation of terahertz nanoantennas by Rabi waves

    SciTech Connect

    Slepyan, G. Ya.; Yerchak, Y. D.; Maksimenko, S. A. [Institute for Nuclear Problems, Belarus State University, Bobruiskaya 11, 220030 Minsk (Belarus); Hoffmann, A. [Institut fuer Festkoerperphysik, Technische Universitaet Berlin, Hardenbergstrasse 36, 10623 Berlin (Germany); Bass, F. G. [Department of Physics, Bar-Ilan University, 52900 Ramat-Gan (Israel)

    2011-10-03

    Theoretical model of quantum dot ring, strongly coupled with classical electromagnetic field, is developed. We demonstrate, that tunnel current in the QD-ring has low-frequency component, excited by Rabi waves, propagating into the ring, and the ring can be considered as a candidate for role of terahertz magnetic loop antenna. The low-frequency current is inspired by the asymmetry of electron tunneling.

  18. Isoscalar spin excitation in 40Ca

    Microsoft Academic Search

    M. Morlet; E. Tomasi-Gustafsson; A. Willis; J. van de Wiele; N. Marty; C. Glashausser; B. N. Johnson; F. T. Baker; D. Beatty; L. Bimbot; C. Djalali; G. W. Edwards; A. Green; J. Guillot; F. Jourdan; H. Langevin-Joliot; L. Rosier; M. Y. Youn

    1992-01-01

    A signature Syd of isoscalar spin-transfer strength has been tested in the inelastic scattering of 400 MeV dueterons from 12C. It was then applied to the study of 40Ca over an angular range from 3° to 7° (momentum transfer range from 0.26 to 0.8 fm-1) and an excitation energy range from 6.25 to 42 MeV. This is the first study

  19. Science Mathematics Engineering

    E-print Network

    Hamlet, Richard

    . Philosophy of Software Engineering II. Mathematics, Science, Engineering III. And for Software EngineeringScience Mathematics Engineering . ­ p.1 #12;Science Mathematics Engineering Science, Computer `Science', . ­ p.1 #12;Science Mathematics Engineering Science, Computer `Science', Mathematics, . ­ p.1

  20. Vacuum-excited surface plasmon polaritons

    NASA Astrophysics Data System (ADS)

    Naylor, Wade

    2015-05-01

    We separate Maxwell's equations for background media that allow for both electric and magnetic time dependence in a generalized Lorenz gauge. In a process analogous to the dynamical Casimir effect (DCE) we discuss how surface plasmon polaritons (SPPs) can be created out of vacuum via the time-dependent variation of a dielectric and magnetic insulator at a metal interface for TM and TE branches, respectively. We suggest how to extend currently proposed DCE experiments to set up and detect these excitations. Numerical simulations (without any approximation) indicate that vacuum-excited SPPs can be of a similar magnitude to the photon creation rate in such experiments. Potential benefits of detecting vacuum-excited SPPs, as opposed to DCE photons, are that parametric enhancement does not require a sealed cavity in the axial direction and the detection apparatus might be able to use simple phase-matching techniques. For the case of constant permeability ? , TM branch SPPs and photons do not suffer from detuning and attenuation like TE photons.

  1. Upper excited state photochemistry of DNA.

    PubMed

    Gut, I G; Farmer, R; Huang, R C; Kochevar, I E

    1993-09-01

    The quantum yields for cyclobutylpyrimidine dimers, alkali-labile sites, and frank strand breaks in double-stranded DNA have been measured using low-intensity radiation at 199.8, 217.8, and 239.5 nm from a Raman-shifted frequency quadrupled Nd:YAG laser. The quantum yield for cyclobutylpyrimidine dimers was also measured using 254 nm radiation from a low-pressure mercury lamp. The quantum yield for cyclobutylpyrimidine dimers is constant within a factor of two between 254 and 199.8 nm except for 239.5 nm, indicating that upper excited singlet states of bases convert efficiently to the lowest singlet state. The quantum yields for alkali-labile sites and frank strand breaks both increase as the wavelength decreases but follow different patterns. These results indicate that alkali-labile sites from a higher excited state of the base, whereas frank strand breaks form by excitation of the sugar-phosphate backbone. PMID:8234462

  2. Excitation of vortex meandering in shear flow

    NASA Astrophysics Data System (ADS)

    Schröttle, Josef; Dörnbrack, Andreas; Schumann, Ulrich

    2015-06-01

    This paper investigates the evolution of a streamwise aligned columnar vortex with vorticity {\\boldsymbol{ ? }} in an axial background shear of magnitude ? by means of linear stability analysis and numerical simulations. A long wave mode of vorticity normal to the plane spanned by the background shear vector {\\boldsymbol{ ? }} and the vorticity of the vortex are excited by an instability. The stationary wave modes of the vertical and lateral vorticity are amplified. In order to form a helical vortex, the lateral and vertical vorticity can be phase shifted by half a wavelength. The linear and nonlinear evolutions of the vortex in the shear flow are studied numerically. Linearized simulations confirm the results of the stability analysis. The nonlinear simulations reveal further evolution of the helix in the shear flow. The linearly excited mode persists in co-existence with evolving smaller scale instabilities until the flow becomes fully turbulent at the time of O(100 {{? }-1}). Turbulent mixing dampens the amplifying mode. The described phenomenon of vortex meandering may serve as an alternative explanation for the excitation of wind turbine wake meandering in the atmospheric boundary layer.

  3. Excitation of a composite structure by collisions

    SciTech Connect

    Newby, N.D. Jr.

    1984-08-01

    A simple model is employed to study the excitation of a composite structure by collisions. The composite structure is a diatomic ''molecule'' composed of two equal point masses joined by a Hooke's law spring of constant, k/sub 1/. This structure, in an unexcited state, makes a one-dimensional head-on collision with a fixed wall. The interaction with the wall is mediated by a second Hooke's law spring of constant, k/sub 2/. After rebounding from the wall the diatom may be in an excited state. The excitation energy is calculated as a function of the hardness of the wall. An eigenvalue problem is solved which yields an infinite number of ..beta..'s (..beta.. = k/sub 1//k/sub 2/) which leave the diatom unexcited. The phenomenon of ''double hitting'' : when a soft structure strikes a hard wall: is discussed. The maximum energy transfer into the internal mode is 23%. An air-track experiment is suggested to check the theoretical predictions.

  4. Vacuum-excited surface plasmon polaritons

    E-print Network

    Wade Naylor

    2015-06-17

    We separate Maxwell's equations for background media that allow for both electric and magnetic time-dependence in a generalized Lorenz gauge. In a process analogous to the dynamical Casimir effect (DCE) we discuss how surface plasmon polaritons (SPP)s can be created out of vacuum, via the time-dependent variation of a dielectric and magnetic insulator at a metal interface for TM and TE branches, respectively. We suggest how to extend currently proposed DCE experiments to set up and detect these excitations. Numerical simulations (without any approximation) indicate that vacuum excited SPPs can be of a similar magnitude to the photon creation rate in such experiments. Potential benefits of detecting vacuum excited SPPs, as opposed to DCE photons, are that parametric enhancement does not require a sealed cavity in the axial direction and the detection apparatus might be able to use simple phase matching techniques. For the case of constant permeability, $\\mu$, TM branch SPPs and photons do not suffer from detuning and attenuation like TE photons.

  5. Excitation energy transfer in the photosystem I

    SciTech Connect

    Webber, Andrew N

    2012-09-25

    Photosystem I is a multimeric pigment protein complex in plants, green alage and cyanobacteria that functions in series with Photosystem II to use light energy to oxidize water and reduce carbon dioxide. The Photosystem I core complex contains 96 chlorophyll a molecules and 22 carotenoids that are involved in light harvesting and electron transfer. In eucaryotes, PSI also has a peripheral light harvesting complex I (LHCI). The role of specific chlorophylls in excitation and electron transfer are still unresolved. In particular, the role of so-called bridging chlorophylls, located between the bulk antenna and the core electron transfer chain, in the transfer of excitation energy to the reaction center are unknown. During the past funding period, site directed mutagenesis has been used to create mutants that effect the physical properties of these key chlorophylls, and to explore how this alters the function of the photosystem. Studying these mutants using ultrafast absorption spectroscopy has led to a better understanding of the process by which excitation energy is transferred from the antenna chlorophylls to the electron transfer chain chlorophylls, and what the role of connecting chlorophylls and A_0 chlorophylls is in this process. We have also used these mutants to investigate whch of the central group of six chlorophylls are involved in the primary steps of charge separation and electron transfer.

  6. Apparatus For Laser Excitation of Lithium Atoms.

    NASA Astrophysics Data System (ADS)

    Daly, James; Flaherty, Suzy; Oxley, Paul

    2006-10-01

    We have constructed and tested a vacuum system and a simple lithium oven. Lithium atoms from this oven will be excited to high principal quantum number by a combination of three lasers. We have also built and tested the hardware needed to operate the first of these lasers. In the future we will study charge transfer collisions between excited lithium atoms and ions to gain a better understanding of the physical properties of fusion, astrophysical, and other types of plasmas. Our vacuum system is assembled from standard conflat vacuum parts and from parts designed and built at Holy Cross. The vacuum environment is maintained by a diffusion pump in conjunction with a cold water trap to prevent pump oil migrating into our vacuum system. Our lithium oven consists of a small steel tube filled with lithium and mounted inside our vacuum system. The oven is heated by high temperature heater tapes. We have reached oven temperatures of over 600C which provides a sufficiently intense Li beam for our needs. The laser used in the first excitation step of lithium is a diode laser operating at 671nm. We have assembled the mechanical structure used to mount the diode laser and collimate its light output. Commercial electronics control the laser diode current and its temperature. Initial tests of the properties of the laser have been made.

  7. Excitation equilibria in plasmas; a classification

    NASA Astrophysics Data System (ADS)

    van der Mullen, J. A. M.

    1990-07-01

    This review gives a classification of the excitation kinetics ruled by electrons in plasmas. It is a study on the atomic state distribution function (ASDF) and its relation with underlying processes, which, for the case of an electron excitation kinetics (EEK) plasma, is merely a competition between free and bound electrons, the same particles in different circumstances. In a quasi steady state the population density of an atomic state results from production-destruction balances in equilibrium. If all balances are proper, i.e., consist of each other's inverse processes, then the ASDF is described by the Boltzmann-Saha relation. In other cases the balance will be denoted as improper, the ASDF will deviate from the equilibrium shape, but reflecting the underlying improper balances, it may give information about the plasma. Four improper balances and their impact on the ASDF are dealt with. An important feature is that improper balances are associated with particle transport. Special attention is paid to the distribution function of the excitation saturation balance in which the overpopulated bound electrons are subjected to frequent interactions with free electrons and the energy distribution of the free electrons is taken over. This distribution, denoted as the bound Maxwell distribution, is experimentally found in several ionizing plasmas. Its recombining counterpart, the deexcitation saturation balance, creates under certain conditions inversion in the ASDF, the basis for the recombination laser.

  8. Simultaneous two-photon excitation of photodynamic therapy agents

    SciTech Connect

    Wachter, E.A.; Fisher, W.G. [Oak Ridge National Lab., TN (United States)]|[Photogen, Inc., Knoxville, TN (United States); Partridge, W.P. [Oak Ridge National Lab., TN (United States); Dees, H.C. [Photogen, Inc., Knoxville, TN (United States); Petersen, M.G. [Univ. of Tennessee, Knoxville, TN (United States). College of Veterinary Medicine

    1998-01-01

    The spectroscopic and photochemical properties of several photosensitive compounds are compared using conventional single-photon excitation (SPE) and simultaneous two-photon excitation (TPE). TPE is achieved using a mode-locked titanium:sapphire laser, the near infrared output of which allows direct promotion of non-resonant TPE. Excitation spectra and excited state properties of both type 1 and type 2 photodynamic therapy (PDT) agents are examined.

  9. Charge transfer excitations from excited state Hartree-Fock subsequent minimization scheme

    SciTech Connect

    Theophilou, Iris, E-mail: i.theophilou@fz-juelich.de [Peter Grunberg Institut (PGI) Forschungszentrum Jülich, D-52425 Jülich (Germany)] [Peter Grunberg Institut (PGI) Forschungszentrum Jülich, D-52425 Jülich (Germany); Tassi, M.; Thanos, S. [Institute for Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems, ‘Demokritos’ National Center for Scientific Research, 15310 Athens (Greece)] [Institute for Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems, ‘Demokritos’ National Center for Scientific Research, 15310 Athens (Greece)

    2014-04-28

    Photoinduced charge-transfer processes play a key role for novel photovoltaic phenomena and devices. Thus, the development of ab initio methods that allow for an accurate and computationally inexpensive treatment of charge-transfer excitations is a topic that nowadays attracts a lot of scientific attention. In this paper we extend an approach recently introduced for the description of single and double excitations [M. Tassi, I. Theophilou, and S. Thanos, Int. J. Quantum Chem. 113, 690 (2013); M. Tassi, I. Theophilou, and S. Thanos, J. Chem. Phys. 138, 124107 (2013)] to allow for the description of intermolecular charge-transfer excitations. We describe an excitation where an electron is transferred from a donor system to an acceptor one, keeping the excited state orthogonal to the ground state and avoiding variational collapse. These conditions are achieved by decomposing the space spanned by the Hartree-Fock (HF) ground state orbitals into four subspaces: The subspace spanned by the occupied orbitals that are localized in the region of the donor molecule, the corresponding for the acceptor ones and two more subspaces containing the virtual orbitals that are localized in the neighborhood of the donor and the acceptor, respectively. Next, we create a Slater determinant with a hole in the subspace of occupied orbitals of the donor and a particle in the virtual subspace of the acceptor. Subsequently we optimize both the hole and the particle by minimizing the HF energy functional in the corresponding subspaces. Finally, we test our approach by calculating the lowest charge-transfer excitation energies for a set of tetracyanoethylene-hydrocarbon complexes that have been used earlier as a test set for such kind of excitations.

  10. Search for excited fermions with the H1 detector

    Microsoft Academic Search

    C. Adloff; S. Aid; M. Anderson; V. Andreev; B. Andrieu; C. Arndt; A. Babaev; J. Bähr; J. Bán; Y. Ban; P. Baranov; E. Barrelet; R. Barschke; W. Bartel; M. Barth; U. Bassler; M. Beck; H. P. Beck; H.-J. Behrend; A. Belousov; Ch. Berger; G. Bernardi; G. Bertrand-Coremans; M. Besançon; R. Beyer; P. Biddulph; P. Bispham; J. C. Bizot; V. Blobel; K. Borras; F. Botterweck; V. Boudry; A. Braemer; W. Braunschweig; V. Brisson; W. Brückner; P. Bruel; D. Bruncko; C. Brune; R. Buchholz; L. Büngener; J. Bürger; F. W. Büsser; A. Buniatian; S. Burke; M. J. Burton; D. Calvet; A. J. Campbell; T. Carli; M. Charlet; D. Clarke; A. B. Clegg; B. Clerbaux; S. Cocks; J. G. Contreras; C. Cormack; J. A. Coughlan; A. Courau; M.-C. Cousinou; G. Cozzika; L. Criegee; D. G. Cussans; J. Cvach; S. Dagoret; J. B. Dainton; W. D. Dau; K. Daum; M. David; C. L. Davis; B. Delcourt; A. De Roeck; E. A. De Wolf; M. Dirkmann; P. Dixon; P. Di Nezza; W. Dlugosz; C. Dollfus; K. T. Donovan; J. D. Dowell; H. B. Dreis; A. Droutskoi; O. Dünger; H. Duhm; J. Ebert; T. R. Ebert; G. Eckerlin; V. Efremenko; S. Egli; R. Eichler; F. Eisele; E. Eisenhandler; E. Elsen; M. Erdmann; W. Erdmann; A. B. Fahr; L. Favart; A. Fedotov; R. Felst; J. Feltesse; J. Ferencei; F. Ferrarotto; K. Flamm; M. Fleischer; M. Flieser; G. Flügge; A. Fomenko; J. Formánek; J. M. Foster; G. Franke; E. Fretwurst; E. Gabathuler; K. Gabathuler; F. Gaede; J. Garvey; J. Gayler; M. Gebauer; H. Genzel; R. Gerhards; A. Glazov; L. Goerlich; N. Gogitidze; M. Goldberg; D. Goldner; K. Golec-Biernat; B. Gonzalez-Pineiro; I. Gorelov; C. Grab; H. Grässler; T. Greenshaw; R. K. Griffiths; G. Grindhammer; A. Gruber; C. Gruber; T. Hadig; D. Haidt; L. Hajduk; T. Haller; M. Hampel; W. J. Haynes; B. Heinemann; G. Heinzelmann; R. C. W. Henderson; H. Henschel; I. Herynek; M. F. Hess; K. Hewitt; W. Hildesheim; K. H. Hiller; C. D. Hilton; J. Hladký; M. Höppner; D. Hoffmann; T. Holtom; R. Horisberger; V. L. Hudgson; M. Hütte; M. Ibbotson; H. Itterbeck; A. Jacholkowska; C. Jacobsson; M. Jaffre; J. Janoth; D. M. Jansen; T. Jansen; L. Jönsson; D. P. Johnson; H. Jung; P. I. P. Kalmus; M. Kander; D. Kant; R. Kaschowitz; U. Kathage; J. Katzy; H. H. Kaufmann; O. Kaufmann; M. Kausch; S. Kazarian; I. R. Kenyon; S. Kermiche; C. Keuker; C. Kiesling; M. Klein; C. Kleinwort; G. Knies; T. Köhler; J. H. Köhne; H. Kolanoski; S. D. Kolya; V. Korbel; P. Kostka; S. K. Kotelnikov; T. Krämerkämper; M. W. Krasny; H. Krehbiel; D. Krücker; H. Küster; M. Kuhlen; T. Kurca; J. Kurzhöfer; D. Lacour; B. Laforge; M. P. J. Landon; W. Lange; U. Langenegger; A. Lebedev; F. Lehner; S. Levonian; G. Lindström; M. Lindstroem; F. Linsel; J. Lipinski; B. List; G. Lobo; P. Loch; J. W. Lomas; G. C. Lopez; V. Lubimov; D. Lüke; L. Lytkin; N. Magnussen; E. Malinovski; R. Maracek; P. Marage; J. Marks; R. Marshall; J. Martens; G. Martin; R. Martin; H.-U. Martyn; J. Martyniak; T. Mavroidis; S. J. Maxfield; S. J. McMahon; A. Mehta; K. Meier; F. Metlica; A. Meyer; H. Meyer; J. Meyer; P.-O. Meyer; A. Migliori; S. Mikocki; D. Milstead; J. Moeck; F. Moreau; J. V. Morris; E. Mroczko; D. Müller; G. Müller; K. Müller; P. Murín; V. Nagovizin; R. Nahnhauer; B. Naroska; Th. Naumann; I. Négri; P. R. Newman; D. Newton; H. K. Nguyen; T. C. Nicholls; F. Niebergall; C. Niebuhr; Ch. Niedzballa; H. Niggli; G. Nowak; G. W. Noyes; T. Nunnemann; M. Nyberg-Werther; M. Oakden; H. Oberlack; J. E. Olsson; D. Ozerov; P. Palmen; E. Panaro; A. Panitch; C. Pascaud; G. D. Patel; H. Pawletta; E. Peppel; E. Perez; J. P. Phillips; A. Pieuchot; D. Pitzl; G. Pope; B. Povh; S. Prell; K. Rabbertz; G. Rädel; P. Reimer; S. Reinshagen; H. Rick; F. Riepenhausen; S. Riess; E. Rizvi; P. Robmann; H. E. Roloff; R. Roosen; K. Rosenbauer; A. Rostovtsev; F. Rouse; C. Royon; K. Rüter; S. Rusakov; K. Rybicki; D. P. C. Sankey; P. Schacht; S. Schiek; S. Schleif; P. Schleper; W. von Schlippe; D. Schmidt; G. Schmidt; L. Schoeffel; A. Schöning; V. Schröder; E. Schuhmann; B. Schwab; F. Sefkow; R. Sell; A. Semenov; V. Shekelyan; I. Sheviakov; L. N. Shtarkov; G. Siegmon; U. Siewert; Y. Sirois; I. O. Skillicorn; P. Smirnov; V. Solochenko; Y. Soloviev; A. Specka; J. Spiekermann; S. Spielman; H. Spitzer; F. Squinabol; P. Steffen; R. Steinberg; H. Steiner; J. Steinhart; B. Stella; A. Stellberger; J. Stier; J. Stiewe; U. Stößlein; K. Stolze; U. Straumann; W. Struczinski; J. P. Sutton; S. Tapprogge; M. Tasevský; V. Tchernyshov; S. Tchetchelnitski; J. Theissen; C. Thiebaux; G. Thompson; N. Tobien; R. Todenhagen; P. Truöl; G. Tsipolitis; J. Turnau; J. Tutas; E. Tzamariudaki; P. Uelkes; A. Usik; S. Valkár; A. Valkárová; C. Vallée; D. Vandenplas; P. Van Esch; P. Van Mechelen; Y. Vazdik; P. Verrecchia; G. Villet; K. Wacker; A. Wagener; M. Wagener; B. Waugh; G. Weber; M. Weber; D. Wegener; A. Wegner; T. Wengler; M. Werner; L. R. West; T. Wilksen; S. Willard

    1997-01-01

    We present a search for excited electrons, neutrinos and quarks using the H1 detector at the ep collider HERA, based on data taken in 1994 with an integrated luminosity of 2.75 pb?1. Radiative decays of excited quarks and neutrinos have been investigated as well as decays of excited electrons into all possible electroweak gauge bosons. No evidence for new particle

  11. Excitability relationships between lower limb myotatic arcs in spasticity

    Microsoft Academic Search

    P J Delwaide; M Cordonnier; M Gadea-Ciria

    1978-01-01

    The excitability of a lower limb myotatic reflex arc is modulated by the antecedent activation of another myotatic arc in the same limb; the changes can be represented by heteronymous excitability curves. This work compares heteronymous excitability curves in spastic and normal subjects. Eighteen patients who showed clear signs of pyramidal tract lesions at a chronic stage were studied. Three

  12. Vibration and acoustic radiation from point excited spherical shells

    Microsoft Academic Search

    E. H. Wong; S. I. Hayek

    1982-01-01

    Two thin aluminum spherical shells were excited by an impedance head at the apex, simulating a mechanical point excitation. The driving point admittance frequency spectra of the shells when excited in air were recorded and at each maximum, the mode shape at resonance was plotted. These measurements were repeated when the shell was suspended in a large water tank. The

  13. Properties of excited xenon atoms in a plasma display panel

    Microsoft Academic Search

    Han S. Uhm; Byoung H. Hong; Phil Y. Oh; Eun H. Choi

    2009-01-01

    The luminance efficiency of a plasma display panel is directly related to the vacuum ultraviolet (VUV) light that is emitted from excited xenon (Xe) atoms and molecules. It is therefore necessary to investigate the properties of excited xenon atoms. This study presents experimental data associated with the behavior of excited xenon atoms in a PDP discharge cell and compares the

  14. Self-trapped excitations in condensed matter physics

    Microsoft Academic Search

    M. Heritier; P. Lederer; G. Montambaux

    1980-01-01

    The authors discuss a general formulation for self-trapped excitations in condensed matter physics. Previously known aspects include lattice polarons, spin polarons, bubblons, etc. New aspects involve collective excitation self-trapping; solidons in liquid He have been suggested as the correct description for rotons. They emphasise the difference of self-trapped excitations with order parameter fluctuations.

  15. 0+Excited States in Nuclei: Critical Signatures of Structure

    NASA Astrophysics Data System (ADS)

    Wood, J. L.

    2015-11-01

    It is emerging from data that excited 0+ states in nuclei are critical signatures of structure. Some examples of excited 0+ states that are reasonably well understood are followed by details, from recent experimental work, of excited 0+ states that are causing major reassessment of some models.

  16. Excitation rate dependence of Auger recombination in silicon

    Microsoft Academic Search

    Patrick E. Hopkins; Edward V. Barnat; Jose L. Cruz-Campa; Robert K. Grubbs; Murat Okandan; Gregory N. Nielson

    2010-01-01

    This work reports on measurements of the Auger recombination coefficients in silicon wafers with pump-probe thermoreflectance techniques operating at two different excitation rates: 250 kHz (low repetition rate) and 80 MHz (high repetition rate). The different excitation frequencies give rise to different thermoreflectance signals in the Si samples, which is ascribed to the excited number density in the conduction band.

  17. Communicating Science through Exhibitions

    NASA Astrophysics Data System (ADS)

    Dusenbery, Paul

    2005-04-01

    It is critically important for the public to better understand the scientific process. Museum exhibitions are an important part of informal science education that can effectively reach public audiences as well as school groups. They provide an important gateway for the public to learn about compelling scientific endeavors. Science exhibitions also provide a marvelous opportunity for scientists to become engaged in the exhibit development process. The Space Science Institute (SSI) is a national leader in producing traveling science exhibitions and their associated educational programming (i.e. interactive websites, educator workshops, public talks, instructional materials). The focus of this presentation will be on two of its exhibit projects: MarsQuest (on tour for four years) and Alien Earths (its tour began early in 2005). MarsQuest is enabling millions of Americans to share in the excitement of the scientific exploration of Mars and to learn more about their own planet in the process. Alien Earths will bring origins-related research and discoveries to students and the American public. It has four interrelated exhibit areas: Our Place in Space, Star Birth, Planet Quest, and Search for Life. Exhibit visitors will explore the awesome events surrounding the birth of stars and planets; they will join scientists in the hunt for planets outside our solar system including those that may be in ``habitable zones'' around other stars; and finally they will be able to learn about how scientists are looking for signs of life beyond Earth. SSI is also developing interactive web sites based on exhibit themes. New technologies are transforming the Web from a static medium to an interactive environment with tremendous potential for informal education and inquiry-based investigations. This talk will focus on the role informal science projects play in effectively communicating science to a broad, public audience.

  18. Science: Secondary.

    ERIC Educational Resources Information Center

    Curriculum Review, 1980

    1980-01-01

    This article reviews and compares five recent secondary science texts: Addison-Wesley Life Science (Gr. 7-9); Prentice-Hall Life Science (Gr. 7-9); Scott Foresman Biology (Gr. 9-12); Biology: Living Systems (Gr. 10-12); and Biology: The Science of Life (Gr. 10-12). (SJL)

  19. Excitation of electrostatic ion cyclotron waves by a power-modulated transversely excited atmosphere (TEA) CO2 laser

    Microsoft Academic Search

    K. Sasaki; T. Fujii; K. Takahashi; M. Nagatsu; T. Tsukishima

    1993-01-01

    Electrostatic plasma waves are excited in a laboratory plasma by means of the ponderomotive force of a high-power, power-modulated transversely excited atmosphere (TEA) CO2 laser beam [W. W. Duley, CO2Lasers (Academic, New York, 1976), Chap. 2.5]. The strengths of the magnetic field, for which the plasma waves are excited selectively, and the group velocity of the excited plasma waves are

  20. Two-photon excited fluorescence microendoscopic imaging using a GRIN lens

    NASA Astrophysics Data System (ADS)

    Yan, Wei; Peng, Xiao; Lin, Danying; Wang, Qi; Gao, Jian; Zhou, Jie; Ye, Tong; Qu, Junle; Niu, Hanben

    2015-03-01

    With the rapid development of life sciences, there is an increasing demand for intravital fluorescence imaging of small animals. However, large dimensions and limited working distances of objective lenses in traditional fluorescence microscopes have limited the imaging applications mostly to superficial tissues. To overcome this disadvantage, researchers have developed the graded-index (GRIN) probes with small diameters for imaging internal organs of small animals in a minimally invasive fashion. Here, we present the development of a fluorescence endoscopic imaging system based on a GRIN lens using two-photon excitation. Experimental results showed that this system could perform dynamic fluorescence microendoscopic imaging and monitor the blood flow in anesthetized living mice using two-photon excitation.

  1. Be/X-Ray Pulsar Binary Science with LOFT

    NASA Technical Reports Server (NTRS)

    Wilson-Hodge, Colleen A.

    2011-01-01

    Accretion disks are ubiquitous in astronomical sources. Accretion powered pulsars are a good test bed for accretion disk physics, because unlike for other objects, the spin of the neutron star is directly observable allowing us to see the effects of angular momentum transfer onto the pulsar. The combination of a sensitive wide-field monitor and the large area detector on LOFT will enable new detailed studies of accretion powered pulsars which I will review. RXTE observations have shown an unusually high number of Be/X-ray pulsar binaries in the SMC. Unlike binaries in the Milky Way, these systems are all at the same distance, allowing detailed population studies using the sensitive LOFT WFM, potentially providing connections to star formation episodes. For Galactic accreting pulsar systems, LOFT will allow measurement of spectral variations within individual pulses, mapping the accretion column in detail for the first time. LOFT will also provide better constraints on magnetic fields in accreting pulsars, allowing measurements of cyclotron features, observations of transitions into the centrifugal inhibition regime, and monitoring of spin-up rate vs flux correlations. Coordinated multi-wavelength observations are crucial to extracting the best science from LOFT from these and numerous other objects.

  2. Biopolitical science.

    PubMed

    Arnhart, Larry

    2010-03-01

    This article develops a theoretical framework for biopolitical science as a science of political animals. This science moves through three levels of deep political history: the universal political history of the species, the cultural political history of the group, and the individual political history of animals in the group. To illustrate the particular application of biopolitical science, this essay shows how this science would help us to understand Abraham Lincoln's Emancipation Proclamation of January 1, 1863. PMID:20812796

  3. iBiology: communicating the process of science.

    PubMed

    Goodwin, Sarah S

    2014-08-01

    The Internet hosts an abundance of science video resources aimed at communicating scientific knowledge, including webinars, massive open online courses, and TED talks. Although these videos are efficient at disseminating information for diverse types of users, they often do not demonstrate the process of doing science, the excitement of scientific discovery, or how new scientific knowledge is developed. iBiology (www.ibiology.org), a project that creates open-access science videos about biology research and science-related topics, seeks to fill this need by producing videos by science leaders that make their ideas, stories, and experiences available to anyone with an Internet connection. PMID:25080124

  4. iBiology: communicating the process of science

    PubMed Central

    Goodwin, Sarah S.

    2014-01-01

    The Internet hosts an abundance of science video resources aimed at communicating scientific knowledge, including webinars, massive open online courses, and TED talks. Although these videos are efficient at disseminating information for diverse types of users, they often do not demonstrate the process of doing science, the excitement of scientific discovery, or how new scientific knowledge is developed. iBiology (www.ibiology.org), a project that creates open-access science videos about biology research and science-related topics, seeks to fill this need by producing videos by science leaders that make their ideas, stories, and experiences available to anyone with an Internet connection. PMID:25080124

  5. Standoff alpha radiation detection via excited state absorption of air

    SciTech Connect

    Yao, Jimmy; Yin, Stuart Shizhuo [Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)] [Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Brenizer, Jack [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)] [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Hui, Rongqing [Department of Electrical Engineering and Computer Science, The University of Kansas, Lawrence, Kansas 66045 (United States)] [Department of Electrical Engineering and Computer Science, The University of Kansas, Lawrence, Kansas 66045 (United States)

    2013-06-24

    A standoff alpha radiation detection technique based on the physical mechanism of excited state absorption of air molecules was explored and is presented in this paper. Instead of directly detecting the radiation via measuring the intensity of radiation induced air fluorescence, the radiation is detected via the excited state absorption of alpha radiation excited/ionized air molecules. Both theoretical analyses and experimental verifications were conducted. The experimental results confirmed that the radiation could be detected via excited state absorption of radiation excited/ionized air molecules at a 10 m standoff distance, which was consistent with the theoretical analyses.

  6. The photodissociation and reaction dynamics of vibrationally excited molecules

    SciTech Connect

    Crim, F.F. [Univ. of Wisconsin, Madison (United States)

    1993-12-01

    This research determines the nature of highly vibrationally excited molecules, their unimolecular reactions, and their photodissociation dynamics. The goal is to characterize vibrationally excited molecules and to exploit that understanding to discover and control their chemical pathways. Most recently the author has used a combination of vibrational overtone excitation and laser induced fluorescence both to characterize vibrationally excited molecules and to study their photodissociation dynamics. The author has also begun laser induced grating spectroscopy experiments designed to obtain the electronic absorption spectra of highly vibrationally excited molecules.

  7. Transfer and excitation with heavy projectiles and targets

    SciTech Connect

    Graham, W.G. (Physics Department, Queen's University, Belefast (Northern Ireland))

    1990-06-01

    It has been shown that projectile excitation and electron capture can occur together in a single encounter between an ion projectile and a target electron. The capture and excitation events can be correlated (Resonant Transfer and Excitation (RTE)) or uncorrelated (Nonresonant Transfer and Excitation (NTE) and Uncorrelated Transfer and Excitation (UTE)). In collisions of intermediate Z projectiles with H{sub 2} and He there is now generally good agreement between experiment and theory but a few existing discrepancies are discussed. There is as yet no theoretical work for heavy projectiles but experimental work is now underway. In heavy targets it appears that the uncorrelated process dominate over RTE.

  8. Welcome to health information science and systems.

    PubMed

    Zhang, Yanchun

    2013-01-01

    Health Information Science and Systems is an exciting, new, multidisciplinary journal that aims to use technologies in computer science to assist in disease diagnoses, treatment, prediction and monitoring through the modeling, design, development, visualization, integration and management of health related information. These computer-science technologies include such as information systems, web technologies, data mining, image processing, user interaction and interface, sensors and wireless networking and are applicable to a wide range of health related information including medical data, biomedical data, bioinformatics data, public health data. PMID:25825653

  9. National Sciences Digital Library: Bilingual Collection

    NSDL National Science Digital Library

    The National Science Digital Library (NSDL) has crafted this special and timely collection from their existing archive of fabulous math and science resources for those educators working with bilingual students. The majority of the non-English language resources are in Spanish, but there are also many resources in Portuguese, French, German, and Italian. Visitors can scroll through the Resource Categories to look over different resources by grade level. It's easy to get excited about the site as it contains hundreds of high quality materials, including podcasts, fact sheets, worksheets, teachers guides, and interactive science lab activities.

  10. Earth Sciences Environmental Earth Sciences,

    E-print Network

    Brierley, Andrew

    84 Earth Sciences­ Environmental Earth Sciences, Geology MGeol (Single Honours Degrees) Earth Sciences BSc (Single Honours Degrees) Environmental Earth Sciences Geology BSc (Joint Honours Degrees) and among the most research-intensive in Europe. Features * The Department of Earth and Environmental

  11. Cognitive Science 1 Cognitive Science

    E-print Network

    ), David Rand (Psychology), Gregory Samanez-Larkin (Psychology) Lecturer Kathryn Davidson Cognitive scienceCognitive Science 1 Cognitive Science Director of undergraduate studies: Joshua Knobe, 102 C, 432-1699, joshua.knobe@yale.edu; www.yale.edu/cogsci FACULTY ASSOCIATED WITH THE PROGRAM IN COGNITIVE SCIENCE

  12. Natural Sciences Tripos EARTH SCIENCES

    E-print Network

    Cambridge, University of

    Natural Sciences Tripos EARTH SCIENCES University of Cambridge Undergraduate Prospectus 2013.indd 1Undergraduate Prospectus 2013.indd 1 29/07/2013 16:44:3529/07/2013 16:44:35 #12;Department of Earth Sciences is the science of the Earth. What is the Earth made of? What processes shape and change it? What's happened

  13. Two-versus one photon excitation laser scanning microscopy: Critical importance of excitation wavelength

    PubMed Central

    Bush, Peter G.; Wokosin, David L.; Hall, Andrew C.

    2008-01-01

    It is often anticipated that two-photon excitation (TPE) laser scanning microscopy should improve cell survival and tissue penetration relative to conventional one-photon excitation (OPE) confocal scanning laser microscopy (CLSM). However few studies have directly compared live cell imaging using one- vs two-photon laser scanning microscopy. We have used calcein-loaded in situ chondrocytes within cartilage as a model for quantitatively comparing these techniques. TPE reduced photo-bleaching and improved cell viability compared to OPE. Using improved detection sensitivity coupled with increased tissue penetration of the near infra-red TPE laser, it was possible to capture images deeper within the cartilage. However, the advantages of TPE vs OPE were strongly dependent on excitation wavelength. We conclude that optimising TPE conditions is essential if the full benefits of this approach are to be realised. PMID:17127269

  14. Science Sampler: A (minty) fresh approach to science fair projects

    NSDL National Science Digital Library

    Nancy Balter

    2007-02-01

    Many students are excited at the prospect of doing a science fair project, but they don't know how to go about asking an appropriate question or designing an experiment to answer their question. This class activity allows students to quickly "do" a class science fair project in order to see how it's done. It's also a great way to introduce concepts of controlling variables and testing multiple subjects using an inexpensive breath mint. Even if you do not do science fair projects with your class, this is a terrific activity for the beginning of the year as an introduction to the process of scientific inquiry. Students discover how to ask a simple question and collect data to answer it in a step-by-step fashion.

  15. Stretched-State Excitations with the

    NASA Astrophysics Data System (ADS)

    Garcia, Luis Alberto Casimiro

    Neutron time-of-fight spectra were obtained for the ^{14}C(p,n) ^{14}N, ^{18 }O(p,n)^{18}F, and ^{30}Si(p,n) ^{30}P reactions at 135 MeV with the beam-swinger system at the Indiana University Cyclotron Facility. Excitation-energy spectra and the differential cross sections for the observed excitations in these reactions were extracted over the momentum transfer range from 0 to 2.7 fm^{-1}. The primary goal of this work was to obtain the strengths and distributions for the "stretched" states. The identification of these states was based on comparisons of the theoretical differential cross sections, performed in a DWIA formalism, with the experimental cross sections. Isospin assignments were based primarily on comparisons of the measured (p,n) and (e,e^') spectroscopic strengths. Candidate (pid_ {5/2},nu{rm p}_sp {3/2}{-1}), J^ pi = 4 ^- T = 0, 1 and 2, 1 hbaromega states, were identified at E_{x} = 8.5, 13.8, 19.5, and 26.7 MeV in the ^{14}C(p,n) ^{14}N reaction, and the corresponding isovector strengths were extracted. The observed 4^--state excitation energies and the strengths are in good agreement with the analog T = 1 and 2, 4^--states observed in the (e,e^') reaction. Large -basis shell-model calculations were found to predict reasonably well the excitation energies; however, these calculations overpredict the strength by a factor of 2, for the T = 1 and 2 components. In the ^{18}O(p,n) ^{18}F reaction at 135 MeV, (pi d_{5/2},nu {rm d}_sp{5/2}{-1 }) 5^+ T = 0 0hbaromega strength was observed, concentrated in a single state, at E_{x} = 1.1 MeV, with 75% of the extreme-single-particle-model (ESPM) strength, in good agreement with a shell-model calculation. No 6^- 1hbaromega strength was observed in this reaction. Candidate (pi {rm d}_{5/2},nu p _sp{3/2}{-1}) J ^pi = 4^- T = 0, 1 and 2, 1hbaromega states, were identified at E_{x} = 3.9, 9.4, 10.2, 11.4, 12.0, 14.4, 15.3, 17.3, 18.0, 19.7, 21.4, and 23.4 MeV. The observed 4^- T = 2 state excitation energies and strengths agree well with the analog states seen in the (e,e^ ') reaction. Shell-model calculations for the 4^- strength, predict reasonably well the excitation energies and strengths for the T = 2 component; viz. the states at 19.7 and 23.4 MeV. In the ^{30}Si(p,n) ^{30}P reaction at 135 MeV, candidate (pi{rm f} _{7/2},nu{rm d}_sp {5/2}{-1}) J^ pi = 6^- T = 0, 1 and possible 2, 1hbaromega states, were identified at E_{x} = 5.8, 6.4, 7.2, 7.7, 8.9, 10.2, 11.3, 13.5, and 17.4 MeV. Preliminary (e,e^') results are in poor agreement with the (p,n) results. One candidate (pi{rm d}_{5/2 },nu{rm d}_sp{5/2 }{-1}) J^pi = 5^+ 0hbar omega state was identified at E_ {x} = 4.3 MeV.

  16. HEASARC - The High Energy Astrophysics Science Archive Research Center

    NASA Technical Reports Server (NTRS)

    Smale, Alan P.

    2011-01-01

    The High Energy Astrophysics Science Archive Research Center (HEASARC) is NASA's archive for high-energy astrophysics and cosmic microwave background (CMB) data, supporting the broad science goals of NASA's Physics of the Cosmos theme. It provides vital scientific infrastructure to the community by standardizing science data formats and analysis programs, providing open access to NASA resources, and implementing powerful archive interfaces. Over the next five years the HEASARC will ingest observations from up to 12 operating missions, while serving data from these and over 30 archival missions to the community. The HEASARC archive presently contains over 37 TB of data, and will contain over 60 TB by the end of 2014. The HEASARC continues to secure major cost savings for NASA missions, providing a reusable mission-independent framework for reducing, analyzing, and archiving data. This approach was recognized in the NRC Portals to the Universe report (2007) as one of the HEASARC's great strengths. This poster describes the past and current activities of the HEASARC and our anticipated developments in coming years. These include preparations to support upcoming high energy missions (NuSTAR, Astro-H, GEMS) and ground-based and sub-orbital CMB experiments, as well as continued support of missions currently operating (Chandra, Fermi, RXTE, Suzaku, Swift, XMM-Newton and INTEGRAL). In 2012 the HEASARC (which now includes LAMBDA) will support the final nine-year WMAP data release. The HEASARC is also upgrading its archive querying and retrieval software with the new Xamin system in early release - and building on opportunities afforded by the growth of the Virtual Observatory and recent developments in virtual environments and cloud computing.

  17. Dynamic Characteristics of Excited Atomic Systems

    NASA Astrophysics Data System (ADS)

    Bezuglov, N. N.; Dimitrijevic, M. S.; Klyucharev, A. N.; Mihajlov, A. A.

    2014-12-01

    The dynamics of excited atom interactions with other atoms, which often lead to associative ionization, is largely governed by stochastic diffusion of the valence electron through Rydberg states prior to the ionization. Such processes are associated with random changes of the energy state of the highly excited electron, and they are likely to influence the nuclear dynamics, especially at subthermal collision energies. Possibilities of manipulation of the chaotic dynamics of Rydberg states require a detailed exploration. For an electron in a given Rydberg state moving in a microwave field, which can be generated via interaction with another atom or molecule, there exists critical field strength, above which motion of the electron in the energy space is chaotic. Recently a way to block the dynamic chaos regime was shown, if a given Rydberg state is located somewhat above the middle between the two other states with the orbital quantum number differing by one, whereby level shifts can be controlled by employing Stark/Zeeman shifts in external DC electric/magnetic fields. The stochastic effects in collisions involving Rydberg particles, in which the initial and final reaction channels are connected via intermediate highly excited collision complexes with multiple crossings of energy levels, can be treated using the dynamic chaos approach (Chirikov criterion, Standard and Keppler mapping of time evolution of the Rydberg electron, solution of the Fokker-Plank- and Langevin-type of equations, etc.). Such approach to obtaining dynamics characteristics is a natural choice, since the treatment of Rydberg electron dynamics as a kind of diffusion process allowing one to bypass the multi-level-crossing problem, which can hardly be solved by conventional quantum chemistry methods.

  18. Adenosine postsynaptically modulates supraoptic neuronal excitability.

    PubMed

    Ponzio, Todd A; Hatton, Glenn I

    2005-01-01

    Effects of adenosine on the excitability of supraoptic nucleus neurons were investigated in whole cell patch-clamp experiments conducted in horizontal slices of rat hypothalamus. Adenosine (10-100 muM) inhibited all neurons tested by reducing or abolishing spontaneous or evoked discharge. Large hyperpolarizations were seen, averaging -6.08 +/- 0.83 mV below resting membrane potential, and action potential durations were significantly reduced by 134 +/- 41 mus in the presence of 100 muM adenosine. The A(1) receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, 1 muM) blocked these effects, whereas the A(1) agonists N(6)-cyclopentyladenosine (CPA) and N(6)-cyclohexyladenosine (CHA) mimicked the actions of adenosine. A(2) receptor contributions to excitability were assessed by application of an A(2) agonist, carboxamidoadenosine (CPCA). This resulted in membrane depolarizations (3.56 +/- 0.65 mV) and maintenance of firing. The presence of endogenous adenosine in the slice was revealed by both the application of the adenosine uptake inhibitor dilazep (1-100 muM), which resulted in a strong inhibition of firing activity, and the application of DPCPX, which induced firing in cells silenced by negative current injection. We tested for postsynaptic actions of adenosine by blocking G protein activation via GDP-beta-S infusion into recorded neurons. Under these conditions, the adenosinergic inhibition of firing and reduction of spike duration were blocked, suggesting the effects were mediated by postsynaptic adenosine receptors. That the effects on excitability could be due to direct activation of adenosine A(1) receptors on supraoptic neurons was further explored immunocytochemically via the co-labeling of magnocellular neurons with polyclonal antibodies raised against the A(1) receptors. It is concluded that adenosine, acting at postsynaptic A(1) receptors, exhibits a powerful inhibitory influence on supraoptic magnocellular activity and is an important endogenous regulator of magnocellular neuroendocrine function. PMID:15356187

  19. Fluorescence lifetime excitation cytometry by kinetic dithering

    PubMed Central

    Li, Wenyan; Vacca, Giacomo; Castillo, Maryann; Houston, Kevin D; Houston, Jessica P

    2014-01-01

    Flow cytometers are powerful high-throughput devices that capture spectroscopic information from individual particles or cells. These instruments provide a means of multi-parametric analyses for various cellular biomarkers or labeled organelles and cellular proteins. However, the spectral overlap of fluorophores limits the number of fluorophores that can be used simultaneously during experimentation. Time-resolved parameters enable the quantification of fluorescence decay kinetics, thus circumventing common issues associated with intensity-based measurements. This contribution introduces fluorescence lifetime excitation cytometry by kinetic dithering (FLECKD) as a method to capture multiple fluorescence lifetimes using a hybrid time-domain approach. The FLECKD approach excites fluorophores by delivering short pulses of light to cells or particles by rapid dithering and facilitates measurement of complex fluorescence decay kinetics by flow cytometry. Our simulations demonstrated a resolvable fluorescence lifetime value as low as 1.8 ns (±0.3 ns) with less than 20% absolute error. Using the FLECKD instrument, we measured the shortest average fluorescence lifetime value of 2.4 ns and found the system measurement error to be ±0.3 ns (SEM), from hundreds of monodisperse and chemically stable fluorescent microspheres. Additionally, we demonstrate the ability to detect two distinct excited state lifetimes from fluorophores in single cells using FLECKD. This approach presents a new ability to resolve multiple fluorescence lifetimes while retaining the fluidic throughput of a cytometry system. The ability to discriminate more than one average fluorescence lifetime expands the current capabilities of high-throughput and intensity-based cytometry assays as the need to tag one single cell with multiple fluorophores is now widespread. PMID:24668857

  20. Large-excitability asymptotics for scroll waves in three-dimensional excitable media.

    PubMed

    Margerit, Daniel; Barkley, Dwight

    2002-09-01

    Three-dimensional scroll waves are considered in a reaction-diffusion model of excitable media in the large excitability limit. Coordinates based on the scroll filament are defined and shown to provide a natural extension of the coordinates used for two-dimensional spiral waves. The leading-order free-boundary equations for interface motion in three dimensions are explicitly derived in these coordinates. Three specific examples are considered: straight twisted scroll waves, axisymmetric scroll waves, and helical scroll waves. The equations for the fields at leading and first order in the core region are given. PMID:12366231

  1. Inductive Reasoning and Kolmogorov Complexity University of Waterloo, Department of Computer Science

    E-print Network

    Vitanyi, Paul M.B.

    Wiskunde en Informatica ABSTRACT This is a sloppy first draft of [J. Comp. System Sciences, 44:2(1992), 343.) There have been old useful principles, new exciting models, and intricate theories scattered in vastly

  2. Form factors and excitations of topological solitons

    SciTech Connect

    Weir, David J.; Rajantie, Arttu [Theoretical Physics Group, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom)

    2011-05-23

    We show how the interaction properties of topological solitons in quantum field theory can be calculated with lattice Monte Carlo simulations. Topologically nontrivial field configurations are key to understanding the nature of the QCD vacuum through, for example, the dual superconductor picture. Techniques that we have developed to understand the excitations and form factors of topological solitons, such as kinks and 't Hooft-Polyakov monopoles, should be equally applicable to chromoelectric flux tubes. We review our results for simple topological solitons and their agreement with exact results, then discuss our progress towards studying objects of interest to high energy physics.

  3. Automatic cytometric device using multiple wavelength excitations

    NASA Astrophysics Data System (ADS)

    Rongeat, Nelly; Ledroit, Sylvain; Chauvet, Laurence; Cremien, Didier; Urankar, Alexandra; Couderc, Vincent; Nérin, Philippe

    2011-05-01

    Precise identification of eosinophils, basophils, and specific subpopulations of blood cells (B lymphocytes) in an unconventional automatic hematology analyzer is demonstrated. Our specific apparatus mixes two excitation radiations by means of an acousto-optics tunable filter to properly control fluorescence emission of phycoerythrin cyanin 5 (PC5) conjugated to antibodies (anti-CD20 or anti-CRTH2) and Thiazole Orange. This way our analyzer combining techniques of hematology analysis and flow cytometry based on multiple fluorescence detection, drastically improves the signal to noise ratio and decreases the spectral overlaps impact coming from multiple fluorescence emissions.

  4. Neuromorphic excitable maps for visual processing.

    PubMed

    Rasche, Christoph

    2007-03-01

    An excitable membrane is described which can perform different visual tasks such as contour detection, contour propagation, image segmentation, and motion detection. The membrane is designed to fit into a neuromorphic multichip system. It consists of a single two-dimensional (2-D) layer of locally connected integrate-and-fire neurons and propagates input in the subthreshold and the above-threshold range. It requires adjustment of only one parameter to switch between the visual tasks. The performance of two spiking membranes of different connectivity is compared, a hexagonally and an octagonally connected membrane. Their hardware and system suitability is discussed. PMID:17385636

  5. Magnetic excitations in nuclei with neutron excess

    E-print Network

    G. Co'; V. De Donno; M. Anguiano; A. M. Lallena

    2012-03-13

    The excitation of the $1^+$, $2^-$ and $3^+$ modes in $^{16}$O, $^{22}$O, $^{24}$O, $^{28}$O, $^{40}$Ca, $^{48}$Ca, $^{52}$Ca and $^{60}$Ca nuclei is studied with self-consistent random phase approximation calculations. Finite-range interactions of Gogny type, containing also tensor-isospin terms, are used. We analyze the evolution of the magnetic resonances with the increasing number of neutrons, the relevance of collective effects, the need of a correct treatment of the continuum and the role of the tensor force.

  6. Magnetoelastic excitations in spin-Peierls systems

    SciTech Connect

    Holicki, Michael; Fehske, Holger; Werner, Ralph

    2001-05-01

    From the random-phase approximation to the spin-Peierls transition, two parameter regimes of phonon softening and hardening are present. Magnetoelastic excitations are discussed in detail for phonons coupled to the exactly solvable model of XY spin chains for both regimes, leading to a modified interpretation of the 30-cm{sup -1} mode in CuGeO{sub 3}. Frustrated Heisenberg chains coupled to phonons satisfactorily describe the pretransitional quasielastic scattering in CuGeO{sub 3}. A real-space interpretation of the quasielastic scattering is given justifying effective Ising-model approaches.

  7. Two photon excitation of atomic oxygen

    NASA Technical Reports Server (NTRS)

    Pindzola, M. S.

    1977-01-01

    A standard perturbation expansion in the atom-radiation field interaction is used to calculate the two photon excitation cross section for 1s(2) 2s(2) 2p(4) p3 to 1s(2) 2s(2) 2p(3) (s4) 3p p3 transition in atomic oxygen. The summation over bound and continuum intermediate states is handled by solving the equivalent inhomogeneous differential equation. Exact summation results differ by a factor of 2 from a rough estimate obtained by limiting the intermediate state summation to one bound state. Higher order electron correlation effects are also examined.

  8. Two-photon excitation of atomic oxygen

    NASA Technical Reports Server (NTRS)

    Pindzola, M. S.

    1978-01-01

    A standard perturbation expansion in the atom-radiation-field interaction is used to calculate the two-photon excitation cross section for the 1s2 2s2 2p4 3p to 1s2 2s2 3(4S)3p 3P transition in atomic oxygen. The lowest-order summation over bound and continuum intermediate states is handled by solving the equivalent inhomogeneous differential equation. Higher-order electron-correlation effects are also examined.

  9. Collisional quenching of highly rotationally excited HF

    NASA Astrophysics Data System (ADS)

    Yang, B.; Walker, K. M.; Forrey, R. C.; Stancil, P. C.; Balakrishnan, N.

    2015-06-01

    Context. Collisional excitation rate coefficients play an important role in the dynamics of energy transfer in the interstellar medium. In particular, accurate rotational excitation rates are needed to interpret microwave and infrared observations of the interstellar gas for nonlocal thermodynamic equilibrium line formation. Aims: Theoretical cross sections and rate coefficients for collisional deexcitation of rotationally excited HF in the vibrational ground state are reported. Methods: The quantum-mechanical close-coupling approach implemented in the nonreactive scattering code MOLSCAT was applied in the cross section and rate coefficient calculations on an accurate 2D HF-He potential energy surface. Estimates of rate coefficients for H and H2 colliders were obtained from the HF-He collisional data with a reduced-potential scaling approach. Results: The calculation of state-to-state rotational quenching cross sections for HF due to He with initial rotational levels up to j = 20 were performed for kinetic energies from 10-5 to 15 000 cm-1. State-to-state rate coefficients for temperatures between 0.1 and 3000 K are also presented. The comparison of the present results with previous work for lowly-excited rotational levels reveals significant differences. In estimating HF-H2 rate coefficients, the reduced-potential method is found to be more reliable than the standard reduced-mass approach. Conclusions: The current state-to-state rate coefficient calculations are the most comprehensive to date for HF-He collisions. We attribute the differences between previously reported data and our results to differences in the adopted interaction potential energy surfaces. The new He rate coefficients can be used in a variety of applications. The estimated H2 and H collision rates can also augment the smaller datasets previously developed for H2 and electrons. Rate coefficient tables are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/578/A65

  10. Ground state and excitations in polyacetylene chains

    SciTech Connect

    Pfeiffer, R.S.; Yoder, G.; Chen, A. [Department of Physics, Auburn University, Alabama 36849-5311 (United States)] [Department of Physics, Auburn University, Alabama 36849-5311 (United States)

    1996-07-01

    While a nearest-neighbor-only Su-Schrieffer-Heeger model cannot distinguish {ital cis}- from {ital trans}-polyacetylene, a simple extension which includes a third-neighbor interaction can. This extended model gives a nondegenerate {ital cis} structure with a larger band gap and a smaller cohesive energy than {ital trans}, and yields the correct order of the total energies of the {ital trans}, {ital cis}-{ital transoid}, and {ital trans}-{ital cisoid} structures. It also produces bound bipolarons or excitons on doubly charged {ital cis} chains. All conformational excitations in both isomers are found to be repelled from the chain ends. {copyright} {ital 1996 The American Physical Society.}

  11. Rydberg excitation of a single trapped ion

    E-print Network

    T. Feldker; P. Bachor; M. Stappel; D. Kolbe; R. Gerritsma; J. Walz; F. Schmidt-Kaler

    2015-06-19

    We demonstrate excitation of a single trapped cold $^{40}$Ca$^+$ ion to Rydberg levels by laser radiation in the vacuum-ultraviolet at 122 nm wavelength. Observed resonances are identified as 3d$^2$D$_{3/2}$ to 51 F, 52 F and 3d$^2$D$_{5/2}$ to 64F. We model the lineshape and our results imply a large state-dependent coupling to the trapping potential. Rydberg ions are of great interest for future applications in quantum computing and simulation, in which large dipolar interactions are combined with the superb experimental control offered by Paul traps.

  12. Excitations in superfluids of atoms and polaritons

    E-print Network

    Pinsker, Florian

    2014-11-11

    Helium [7, 8] and now is referred to as Gross-Pitaevskii equation (GPE). Solutions to the NLSE or GPE include such phe- nomena as solitons, quantum vortices or quantum vortex rings. These elementary and 9 topologically stable excitations are spatially... , vectors of F(H1) are sequences ? = {?i}i?0 (1.1.15) with ?i ? Hi and must satisfy ???2 = ? n?N0 ??n? 2 product of states in F(H1) is defined as ??,?? = ? i?N0 ??i, ?i?, (1.1.17) so the Fock space has the structure of a Hilbert space...

  13. Effects of ionizing radiation on hippocampal excitability

    SciTech Connect

    Pellmar, T.C.; Tolliver, J.M.

    1986-01-01

    Ionizing radiation causes striking changes in hippocampal activity in vivo. Changes in neuronal firing patterns and spiking activity in electroencephalographic recordings appear at doses as low as 4 Gy. Accompanying exposure to ionizing radiation is a breakdown in blood brain barrier and a decrease in cerebral blood flow. In an effort to define the mechanisms of radiation damage to neuronal excitability, without these complicating factors, the effects of radiation on neuronal activity in hippocampal slices were investigated. Damage is likely to result from generation of free radicals. Since peroxide mixed with iron produces hydroxyl free radicals through the Fenton reaction, peroxidative damage was evaluated on hippocampal slices for comparison.

  14. On rotational solutions for elliptically excited pendulum

    E-print Network

    Anton O. Belyakov

    2010-12-30

    The author considers the planar rotational motion of the mathematical pendulum with its pivot oscillating both vertically and horizontally, so the trajectory of the pivot is an ellipse close to a circle. The analysis is based on the exact rotational solutions in the case of circular pivot trajectory and zero gravity. The conditions for existence and stability of such solutions are derived. Assuming that the amplitudes of excitations are not small while the pivot trajectory has small ellipticity the approximate solutions are found both for high and small linear damping. Comparison between approximate and numerical solutions is made for different values of the damping parameter.

  15. Excited intruder states in {sup 32}Mg

    SciTech Connect

    Tripathi, Vandana; Tabor, S. L.; Bender, P.; Hoffman, C. R.; Lee, Sangjin; Pepper, K.; Perry, M.; Utsuno, Y.; Otsuka, T. [Department of Physics, Florida State University, Tallahassee, Florida 32306 (United States); Advanced Science Research Centre, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Department of Physics and Center for Nuclear Study, University of Tokyo, Hongo, Tokyo 113-0033, Japan and RIKEN, Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Mantica, P. F.; Pinter, J. S.; Stoker, J. B. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Department of Chemistry, Michigan State University, East Lansing, Michigan 48824 (United States); Cook, J. M. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Department of Physics, Michigan State University, East Lansing, Michigan 48824 (United States); Pereira, J.; Weisshaar, D. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States)

    2008-03-15

    The low energy level structure of N=20 {sup 32}Mg obtained via {beta}-delayed {gamma} spectroscopy is reported. The level structure of {sup 32}Mg is found to be completely dominated by intruders. An inversion between the 1p-1h and 3p-3h states is observed for the negative parity states, similar to the 0p-0h and 2p-2h inversion for the positive parity states in these N{approx}20 nuclei. The intruder excited states, both positive and negative parity, are reasonably explained by Monte Carlo shell model calculations, which suggest a shrinking N=20 shell gap with decreasing Z.

  16. PHOTOSYNTHESIS: Coherent Excitation in the Antenna Complex

    NSDL National Science Digital Library

    M. Orrit (CNRS and Université Bordeaux; )

    1999-07-16

    Access to the article is free, however registration and sign-in are required. Photosynthesis is key to life on Earth, and the exact mechanisms by which light is harvested and converted into chemical energy remain the subject of intense research. Orrit (page 349) discusses the implications of a single molecule study by van Oijen et al. (page 400), which sheds light on the delocalization of excited states in the antenna complex that harvests and funnels light energy into the reaction center. Subtle structural distortions can also be discerned from the optical spectra, complementing information obtained from x-ray structures.

  17. Favored neutron excitations in superdeformed 147Gd

    NASA Astrophysics Data System (ADS)

    Theisen, Ch.; Khadiri, N.; Vivien, J. P.; Ragnarsson, I.; Beausang, C. W.; Beck, F. A.; Belier, G.; Byrski, T.; Curien, D.; de France, G.; Disdier, D.; Duchêne, G.; Finck, Ch.; Flibotte, S.; Gall, B.; Haas, B.; Hanine, H.; Herskind, B.; Kharraja, B.; Merdinger, J. C.; Nourreddine, A.; Nyakó, B. M.; Perez, G. E.; Prévost, D.; Stezowski, O.; Rauch, V.; Rigollet, C.; Savajols, H.; Sharpey-Schafer, J.; Twin, P. J.; Wei, L.; Zuber, K.

    1996-12-01

    Four new superdeformed (SD) bands have been observed in 147Gd using the EUROGAM II spectrometer. By comparison with 146,148,149Gd SD bands, we use the effective alignment to assign excited band configurations, with the support of the Nilsson-Strutinsky cranking formalism. The effect of the crossing of the [642]5/2 and [651]1/2 neutron orbitals lying just below the magic N=86 SD shell gap has been investigated for the 146,147,148Gd bands. Evidence for the [411]1/2 orbital is also given.

  18. Hadronic decays of the highly excited resonances

    NASA Astrophysics Data System (ADS)

    Ge, Jing; Ye, Dan-Dan; Zhang, Ailin

    2015-05-01

    Hadronic decays of the highly excited resonances have been studied in the model. The widths of all possible hadronic decay channels of the have been computed. , , , , and can be produced from hadronic decays of the , and the relevant hadronic decay widths have been particularly paid attention to. The hadronic decay widths of to or may be large, and the numerical results are different in different assignments of and . The hadronic decay widths of to , or are very small, and different in different assignments of.

  19. Sensing combustion intermediates by femtosecond filament excitation.

    PubMed

    Li, He-Long; Xu, Huai-Liang; Yang, Bo-Si; Chen, Qi-Dai; Zhang, Tao; Sun, Hong-Bo

    2013-04-15

    Simultaneous monitoring of multiple combustion intermediates using femtosecond filament-induced nonlinear spectroscopy is demonstrated. Clean fluorescence emissions from free radicals CH, CN, NH, OH, and C(2), as well as atomic C and H, are observed when a femtosecond filament is formed in the laminar ethanol/air flame on an alcohol burner. The fluorescence signals of these species are found to vary as functions of the position of interaction of the filament with the flame along the vertical axis of the central combusting flow, opening up a possibility for remote combustion diagnostic in engines by the excitation of femtosecond laser filament. PMID:23595448

  20. Isoscalar spin excitation in sup 40 Ca

    Microsoft Academic Search

    M. Morlet; E. Tomasi-Gustafsson; A. Willis; J. Van de Wiele; N. Marty; C. Glashausser; B. N. Johnson; F. T. Baker; D. Beatty; L. Bimbot; C. Djalali; G. W. R. Edwards; A. Green; J. Guillot; F. Jourdan; H. Langevin-Joliot; L. Rosier; M. Y. Youn

    1992-01-01

    A signature {ital S}{sub {ital d}}{sup {ital y}} of isoscalar spin-transfer strength has been tested in the inelastic scattering of 400 MeV dueterons from ¹²C. It was then applied to the study of ⁴°Ca over an angular range from 3° to 7° (momentum transfer range from 0.26 to 0.8 fm⁻¹) and an excitation energy range from 6.25 to 42 MeV.